diff --git a/MANIFEST b/MANIFEST
index a2eccc242..e49804081 100644
--- a/MANIFEST
+++ b/MANIFEST
@@ -24,6 +24,7 @@ lib/Slic3r/Format/STL.pm
 lib/Slic3r/Geometry.pm
 lib/Slic3r/Geometry/Clipper.pm
 lib/Slic3r/GUI.pm
+lib/Slic3r/GUI/Dashboard.pm
 lib/Slic3r/GUI/OptionsGroup.pm
 lib/Slic3r/GUI/SkeinPanel.pm
 lib/Slic3r/Layer.pm
@@ -33,7 +34,6 @@ lib/Slic3r/Polygon.pm
 lib/Slic3r/Polyline.pm
 lib/Slic3r/Print.pm
 lib/Slic3r/Print/Object.pm
-lib/Slic3r/Skein.pm
 lib/Slic3r/Surface.pm
 lib/Slic3r/SVG.pm
 lib/Slic3r/TriangleMesh.pm
diff --git a/README.markdown b/README.markdown
index 2bd0beda1..8e25787b7 100644
--- a/README.markdown
+++ b/README.markdown
@@ -50,7 +50,7 @@ Roadmap includes the following goals:
 
 * output some statistics;
 * support material for internal perimeters;
-* new and better GUI;
+* more GUI work;
 * more fill patterns.
 
 ## Is it usable already? Any known limitation?
@@ -95,7 +95,7 @@ The author is Alessandro Ranellucci (me).
         --post-process      Generated G-code will be processed with the supplied script;
                             call this more than once to process through multiple scripts.
         --export-svg        Export a SVG file containing slices instead of G-code.
-        --merge             If multiple files are supplied, they will be composed into a single 
+        -m, --merge         If multiple files are supplied, they will be composed into a single 
                             print rather than processed individually.
       
       Printer options:
diff --git a/lib/Slic3r.pm b/lib/Slic3r.pm
index adb615ca3..3b77246b5 100644
--- a/lib/Slic3r.pm
+++ b/lib/Slic3r.pm
@@ -33,7 +33,6 @@ use Slic3r::Polygon;
 use Slic3r::Polyline;
 use Slic3r::Print;
 use Slic3r::Print::Object;
-use Slic3r::Skein;
 use Slic3r::Surface;
 use Slic3r::TriangleMesh;
 use Slic3r::TriangleMesh::IntersectionLine;
diff --git a/lib/Slic3r/Config.pm b/lib/Slic3r/Config.pm
index e504171ab..2647c9955 100644
--- a/lib/Slic3r/Config.pm
+++ b/lib/Slic3r/Config.pm
@@ -16,8 +16,8 @@ our $Options = {
         cli     => 'notes=s',
         type    => 's',
         multiline => 1,
-        width   => 350,
-        height  => 300,
+        width   => 220,
+        height  => 130,
         serialize   => sub { join '\n', split /\R/, $_[0] },
         deserialize => sub { join "\n", split /\\n/, $_[0] },
     },
@@ -408,7 +408,7 @@ our $Options = {
         type    => 'i',
     },
     'bed_size' => {
-        label   => 'Bed size for autoarrange (mm)',
+        label   => 'Bed size (mm)',
         cli     => 'bed-size=s',
         type    => 'point',
         serialize   => sub { join ',', @{$_[0]} },
diff --git a/lib/Slic3r/Fill.pm b/lib/Slic3r/Fill.pm
index 520278aa5..677f3c5f2 100644
--- a/lib/Slic3r/Fill.pm
+++ b/lib/Slic3r/Fill.pm
@@ -11,7 +11,7 @@ use Slic3r::Fill::Line;
 use Slic3r::Fill::OctagramSpiral;
 use Slic3r::Fill::PlanePath;
 use Slic3r::Fill::Rectilinear;
-use Slic3r::Geometry qw(scale shortest_path);
+use Slic3r::Geometry qw(X Y scale shortest_path);
 use Slic3r::Geometry::Clipper qw(union_ex diff_ex);
 
 
@@ -34,7 +34,8 @@ sub BUILD {
     $self->fillers->{$_} ||= $FillTypes{$_}->new(print => $self->print)
         for ('rectilinear', $Slic3r::fill_pattern, $Slic3r::solid_fill_pattern);
     
-    my $max_print_dimension = $self->print->max_length * sqrt(2);
+    my $print_size = $self->print->size;
+    my $max_print_dimension = ($print_size->[X] > $print_size->[Y] ? $print_size->[X] : $print_size->[Y]) * sqrt(2);
     $_->max_print_dimension($max_print_dimension) for values %{$self->fillers};
 }
 
diff --git a/lib/Slic3r/Fill/Honeycomb.pm b/lib/Slic3r/Fill/Honeycomb.pm
index 8f76bfd9f..aa54cb045 100644
--- a/lib/Slic3r/Fill/Honeycomb.pm
+++ b/lib/Slic3r/Fill/Honeycomb.pm
@@ -39,7 +39,8 @@ sub fill_surface {
         
         # adjust actual bounding box to the nearest multiple of our hex pattern
         # and align it so that it matches across layers
-        my $bounding_box = [ 0, 0, $self->print->total_x_length, $self->print->total_y_length ];
+        my $print_bounding_box = $self->print->bounding_box;
+        my $bounding_box = [ 0, 0, $print_bounding_box->[X2], $print_bounding_box->[Y2] ];
         {
             my $bb_polygon = Slic3r::Polygon->new([
                 [ $bounding_box->[X1], $bounding_box->[Y1] ],
diff --git a/lib/Slic3r/GUI.pm b/lib/Slic3r/GUI.pm
index 5a24cbfe7..b441036a5 100644
--- a/lib/Slic3r/GUI.pm
+++ b/lib/Slic3r/GUI.pm
@@ -4,6 +4,7 @@ use warnings;
 use utf8;
 
 use FindBin;
+use Slic3r::GUI::Dashboard;
 use Slic3r::GUI::OptionsGroup;
 use Slic3r::GUI::SkeinPanel;
 
@@ -65,4 +66,22 @@ sub About {
     Wx::AboutBox($info);
 }
 
+sub catch_error {
+    my ($self, $cb) = @_;
+    if (my $err = $@) {
+        $cb->() if $cb;
+        Wx::MessageDialog->new($self, $err, 'Error', &Wx::wxOK | &Wx::wxICON_ERROR)->ShowModal;
+        return 1;
+    }
+    return 0;
+}
+
+sub warning_catcher {
+    my ($self) = @_;
+    return sub {
+        my $message = shift;
+        Wx::MessageDialog->new($self, $message, 'Warning', &Wx::wxOK | &Wx::wxICON_WARNING)->ShowModal;
+    };
+}
+
 1;
diff --git a/lib/Slic3r/GUI/Dashboard.pm b/lib/Slic3r/GUI/Dashboard.pm
new file mode 100644
index 000000000..dd9ee77c2
--- /dev/null
+++ b/lib/Slic3r/GUI/Dashboard.pm
@@ -0,0 +1,544 @@
+package Slic3r::GUI::Dashboard;
+use strict;
+use warnings;
+use utf8;
+
+use File::Basename qw(basename dirname);
+use Math::ConvexHull qw(convex_hull);
+use Slic3r::Geometry qw(X Y X1 Y1 X2 Y2 scale unscale);
+use Wx qw(:sizer :progressdialog wxOK wxICON_INFORMATION wxICON_WARNING wxICON_ERROR wxICON_QUESTION
+    wxOK wxCANCEL wxID_OK wxFD_OPEN wxFD_SAVE wxDEFAULT wxNORMAL);
+use Wx::Event qw(EVT_BUTTON EVT_PAINT EVT_MOUSE_EVENTS EVT_LIST_ITEM_SELECTED EVT_LIST_ITEM_DESELECTED);
+use base 'Wx::Panel';
+
+sub new {
+    my $class = shift;
+    my ($parent) = @_;
+    my $self = $class->SUPER::new($parent, -1);
+    
+    $self->{canvas} = Wx::Panel->new($self, -1, [-1, -1], [300, 300]);
+    $self->{canvas}->SetBackgroundColour(Wx::wxWHITE);
+    EVT_PAINT($self->{canvas}, \&repaint);
+    EVT_MOUSE_EVENTS($self->{canvas}, \&mouse_event);
+    
+    $self->{objects_brush} = Wx::Brush->new(Wx::Colour->new(210,210,210), &Wx::wxSOLID);
+    $self->{selected_brush} = Wx::Brush->new(Wx::Colour->new(255,128,128), &Wx::wxSOLID);
+    $self->{transparent_brush} = Wx::Brush->new(Wx::Colour->new(0,0,0), &Wx::wxTRANSPARENT);
+    $self->{grid_pen} = Wx::Pen->new(Wx::Colour->new(230,230,230), 1, &Wx::wxSOLID);
+    $self->{skirt_pen} = Wx::Pen->new(Wx::Colour->new(150,150,150), 1, &Wx::wxSOLID);
+    
+    $self->{list} = Wx::ListView->new($self, -1, [-1, -1], [-1, 180], &Wx::wxLC_SINGLE_SEL | &Wx::wxLC_REPORT | &Wx::wxBORDER_DEFAULT);
+    $self->{list}->InsertColumn(0, "Name", &Wx::wxLIST_FORMAT_LEFT, 300);
+    $self->{list}->InsertColumn(1, "Copies", &Wx::wxLIST_FORMAT_CENTER, 50);
+    $self->{list}->InsertColumn(2, "Scale", &Wx::wxLIST_FORMAT_CENTER, 50);
+    EVT_LIST_ITEM_SELECTED($self, $self->{list}, \&list_item_selected);
+    EVT_LIST_ITEM_DESELECTED($self, $self->{list}, \&list_item_deselected);
+    
+    $self->{btn_load} = Wx::Button->new($self, -1, "Add…");
+    $self->{btn_remove} = Wx::Button->new($self, -1, "Remove");
+    $self->{btn_increase} = Wx::Button->new($self, -1, "+1 copy");
+    $self->{btn_decrease} = Wx::Button->new($self, -1, "-1 copy");
+    $self->{btn_rotate45cw} = Wx::Button->new($self, -1, "Rotate by 45° (cw)");
+    $self->{btn_rotate45ccw} = Wx::Button->new($self, -1, "Rotate by 45° (ccw)");
+    $self->{btn_reset} = Wx::Button->new($self, -1, "Clean");
+    $self->{btn_arrange} = Wx::Button->new($self, -1, "Autoarrange");
+    $self->{btn_changescale} = Wx::Button->new($self, -1, "Change Scale…");
+    $self->{btn_export_gcode} = Wx::Button->new($self, -1, "Export G-code…");
+    $self->{btn_export_gcode}->SetDefault;
+    $self->{$_}->SetWindowVariant(&Wx::wxWINDOW_VARIANT_SMALL) for grep /^btn_/, keys %$self;
+    $self->selection_changed(0);
+    $self->object_list_changed;
+    EVT_BUTTON($self, $self->{btn_load}, \&load);
+    EVT_BUTTON($self, $self->{btn_remove}, \&remove);
+    EVT_BUTTON($self, $self->{btn_increase}, \&increase);
+    EVT_BUTTON($self, $self->{btn_decrease}, \&decrease);
+    EVT_BUTTON($self, $self->{btn_rotate45cw}, sub { $_[0]->rotate(45) });
+    EVT_BUTTON($self, $self->{btn_rotate45ccw}, sub { $_[0]->rotate(-45) });
+    EVT_BUTTON($self, $self->{btn_reset}, \&reset);
+    EVT_BUTTON($self, $self->{btn_arrange}, \&arrange);
+    EVT_BUTTON($self, $self->{btn_changescale}, \&changescale);
+    EVT_BUTTON($self, $self->{btn_export_gcode}, \&export_gcode);
+    
+    $self->SetDropTarget(Slic3r::GUI::Dashboard::DropTarget->new($self));
+    
+    # calculate scaling factor for preview
+    {
+        # supposing the preview canvas is square, calculate the scaling factor
+        # to constrain print bed area inside preview
+        my $canvas_side = $self->{canvas}->GetSize->GetWidth;
+        my $bed_largest_side = $Slic3r::bed_size->[X] > $Slic3r::bed_size->[Y]
+            ? $Slic3r::bed_size->[Y] : $Slic3r::bed_size->[X];
+        $self->{scaling_factor} = $canvas_side / $bed_largest_side;
+    }
+    
+    $self->{print} = Slic3r::Print->new;
+    $self->{thumbnails} = [];       # polygons, each one aligned to 0,0
+    $self->{scale} = [];
+    $self->{object_previews} = [];  # [ obj_idx, copy_idx, positioned polygon ]
+    $self->{selected_objects} = [];
+    $self->recenter;
+    
+    {
+        my $buttons1 = Wx::BoxSizer->new(wxVERTICAL);
+        $buttons1->Add($self->{"btn_$_"})
+            for qw(load remove reset arrange export_gcode);
+        
+        my $buttons2 = Wx::BoxSizer->new(wxVERTICAL);
+        $buttons2->Add($self->{"btn_$_"})
+            for qw(increase decrease rotate45cw rotate45ccw changescale);
+        
+        my $buttons_sizer = Wx::BoxSizer->new(wxHORIZONTAL);
+        $buttons_sizer->Add($_) for ($buttons1, $buttons2);
+        
+        my $vertical_sizer = Wx::BoxSizer->new(wxVERTICAL);
+        $vertical_sizer->Add($self->{list}, 0, wxEXPAND | wxALL);
+        $vertical_sizer->Add($buttons_sizer);
+        
+        my $sizer = Wx::BoxSizer->new(wxHORIZONTAL);
+        $sizer->Add($self->{canvas}, 0, wxALL, 10);
+        $sizer->Add($vertical_sizer, 1, wxEXPAND | wxALL, 10);
+        $sizer->SetSizeHints($self);
+        $self->SetSizer($sizer);
+    }
+    return $self;
+}
+
+sub load {
+    my $self = shift;
+    
+    my $dir = $Slic3r::GUI::SkeinPanel::last_skein_dir || $Slic3r::GUI::SkeinPanel::last_config_dir || "";
+    my $dialog = Wx::FileDialog->new($self, 'Choose a STL or AMF file:', $dir, "", $Slic3r::GUI::SkeinPanel::model_wildcard, wxFD_OPEN);
+    if ($dialog->ShowModal != wxID_OK) {
+        $dialog->Destroy;
+        return;
+    }
+    my $input_file = $dialog->GetPaths;
+    $dialog->Destroy;
+    return $self->load_file($input_file);
+}
+
+sub load_file {
+    my $self = shift;
+    my ($input_file) = @_;
+    
+    $Slic3r::GUI::SkeinPanel::last_input_file = $input_file;
+    
+    local $SIG{__WARN__} = Slic3r::GUI::warning_catcher($self);
+    my $object = $self->{print}->add_object_from_file($input_file);
+    my $obj_idx = $#{$self->{print}->objects};
+    $self->{print}->arrange_objects;
+    
+    $self->{list}->InsertStringItem($obj_idx, basename($input_file));
+    $self->{list}->SetItem($obj_idx, 1, "1");
+    $self->{list}->SetItem($obj_idx, 2, "100%");
+    $self->{list}->Select($obj_idx, 0);
+    push @{$self->{scale}}, 1;
+    
+    $self->make_thumbnail($obj_idx);
+    $self->recenter;
+    $self->{canvas}->Refresh;
+    $self->{list}->Update;
+    $self->{list}->Select($obj_idx, 1);
+    $self->object_list_changed;
+}
+
+sub remove {
+    my $self = shift;
+    
+    foreach my $pobj (@{$self->{selected_objects}}) {
+        my ($obj_idx, $copy_idx) = ($pobj->[0], $pobj->[1]);
+        $self->{print}->copies->[$obj_idx][$copy_idx] = undef;
+    }
+    
+    my @objects_to_remove = ();
+    for my $obj_idx (0 .. $#{$self->{print}->objects}) {
+        my $copies = $self->{print}->copies->[$obj_idx];
+        
+        # filter out removed copies
+        @$copies = grep defined $_, @$copies;
+        
+        # update copies count in list
+        $self->{list}->SetItem($obj_idx, 1, scalar @$copies);
+        
+        # if no copies are left, remove the object itself
+        push @objects_to_remove, $obj_idx if !@$copies;
+    }
+    for my $obj_idx (sort { $b <=> $a } @objects_to_remove) {
+        splice @{$self->{print}->objects}, $obj_idx, 1;
+        splice @{$self->{print}->copies}, $obj_idx, 1;
+        splice @{$self->{thumbnails}}, $obj_idx, 1;
+        splice @{$self->{scale}}, $obj_idx, 1;
+        $self->{list}->DeleteItem($obj_idx);
+    }
+    
+    $self->{selected_objects} = [];
+    $self->selection_changed(0);
+    $self->object_list_changed;
+    $self->recenter;
+    $self->{canvas}->Refresh;
+}
+
+sub reset {
+    my $self = shift;
+    
+    @{$self->{print}->objects} = ();
+    @{$self->{print}->copies} = ();
+    @{$self->{thumbnails}} = ();
+    @{$self->{scale}} = ();
+    $self->{list}->DeleteAllItems;
+    
+    $self->{selected_objects} = [];
+    $self->selection_changed(0);
+    $self->object_list_changed;
+    $self->{canvas}->Refresh;
+}
+
+sub increase {
+    my $self = shift;
+    
+    my $obj_idx = $self->selected_object_idx;
+    my $copies = $self->{print}->copies->[$obj_idx];
+    push @$copies, [ $copies->[-1]->[X] + scale 10, $copies->[-1]->[Y] + scale 10 ];
+    $self->{list}->SetItem($obj_idx, 1, scalar @$copies);
+    $self->arrange;
+}
+
+sub decrease {
+    my $self = shift;
+    
+    my $obj_idx = $self->selected_object_idx;
+    $self->{selected_objects} = [ +(grep { $_->[0] == $obj_idx } @{$self->{object_previews}})[-1] ];
+    $self->remove;
+    
+    if ($self->{print}->objects->[$obj_idx]) {
+        $self->{list}->Select($obj_idx, 0);
+        $self->{list}->Select($obj_idx, 1);
+    }
+}
+
+sub rotate {
+    my $self = shift;
+    my ($angle) = @_;
+    
+    my $obj_idx = $self->selected_object_idx;
+    my $object = $self->{print}->objects->[$obj_idx];
+    
+    # rotate, realign to 0,0 and update size
+    $object->mesh->rotate($angle);
+    $object->mesh->align_to_origin;
+    my @size = $object->mesh->size;
+    $object->x_length($size[X]);
+    $object->y_length($size[Y]);
+    
+    $self->make_thumbnail($obj_idx);
+    $self->arrange;
+    $self->recenter;
+    $self->{canvas}->Refresh;
+}
+
+sub arrange {
+    my $self = shift;
+    
+    $self->{print}->arrange_objects;
+    $self->recenter;
+    $self->{canvas}->Refresh;
+}
+
+sub changescale {
+    my $self = shift;
+    
+    my $obj_idx = $self->selected_object_idx;
+    my $scale = $self->{scale}[$obj_idx];
+    $scale = Wx::GetNumberFromUser("", "Enter the scale % for the selected object:", "Scale", $scale*100, 0, 1000, $self);
+    return if !$scale || $scale == -1;
+    
+    my $object = $self->{print}->objects->[$obj_idx];
+    my $mesh = $object->mesh;
+    $mesh->scale($scale/100 / $self->{scale}[$obj_idx]);
+    $object->mesh->align_to_origin;
+    my @size = $object->mesh->size;
+    $object->x_length($size[X]);
+    $object->y_length($size[Y]);
+    
+    $self->{scale}[$obj_idx] = $scale/100;
+    $self->{list}->SetItem($obj_idx, 2, "$scale%");
+    
+    $self->{print}->arrange_objects;
+    $self->make_thumbnail($obj_idx);
+    $self->recenter;
+    $self->{canvas}->Refresh;
+}
+
+sub export_gcode {
+    my $self = shift;
+    
+    my $process_dialog;
+    eval {
+        # validate configuration
+        Slic3r::Config->validate;
+        
+        my $print = $self->{print};
+        
+        # select output file
+        my $output_file = $main::opt{output};
+        {
+            $output_file = $print->expanded_output_filepath($output_file);
+            my $dlg = Wx::FileDialog->new($self, 'Save G-code file as:', dirname($output_file),
+                basename($output_file), $Slic3r::GUI::SkeinPanel::gcode_wildcard, wxFD_SAVE);
+            if ($dlg->ShowModal != wxID_OK) {
+                $dlg->Destroy;
+                return;
+            }
+            $output_file = $Slic3r::GUI::SkeinPanel::last_output_file = $dlg->GetPath;
+            $dlg->Destroy;
+        }
+        
+        # show processbar dialog
+        $process_dialog = Wx::ProgressDialog->new('Slicing...', "Processing input file...", 
+            100, $self, 0);
+        $process_dialog->Pulse;
+        
+        {
+            my @warnings = ();
+            local $SIG{__WARN__} = sub { push @warnings, $_[0] };
+            my %params = (
+                output_file => $output_file,
+                status_cb   => sub {
+                    my ($percent, $message) = @_;
+                    if (&Wx::wxVERSION_STRING =~ / 2\.(8\.|9\.[2-9])/) {
+                        $process_dialog->Update($percent, "$message...");
+                    }
+                },
+                keep_meshes => 1,
+            );
+            if ($params{export_svg}) {
+                $print->export_svg(%params);
+            } else {
+                $print->export_gcode(%params);
+            }
+            Slic3r::GUI::warning_catcher($self)->($_) for @warnings;
+        }
+        $process_dialog->Destroy;
+        undef $process_dialog;
+        
+        my $message = "Your files were successfully sliced";
+        $message .= sprintf " in %d minutes and %.3f seconds",
+            int($print->processing_time/60),
+            $print->processing_time - int($print->processing_time/60)*60
+                if $print->processing_time;
+        $message .= ".";
+        eval {
+            $self->{growler}->notify(Event => 'SKEIN_DONE', Title => 'Slicing Done!', Message => $message)
+                if ($self->{growler});
+        };
+        Wx::MessageDialog->new($self, $message, 'Done!', 
+            wxOK | wxICON_INFORMATION)->ShowModal;
+    };
+    Slic3r::GUI::catch_error($self, sub { $process_dialog->Destroy if $process_dialog });
+}
+
+sub make_thumbnail {
+    my $self = shift;
+    my ($obj_idx) = @_;
+    
+    my $object = $self->{print}->objects->[$obj_idx];
+    my @points = map [ @$_[X,Y] ], @{$object->mesh->vertices};
+    my $convex_hull = Slic3r::Polygon->new(convex_hull(\@points));
+    for (@$convex_hull) {
+        @$_ = map $self->to_pixel($_), @$_;
+    }
+    $convex_hull->simplify(0.3);
+    $self->{thumbnails}->[$obj_idx] = $convex_hull;
+}
+
+sub recenter {
+    my $self = shift;
+    
+    # calculate displacement needed to center the print
+    my @print_bb = $self->{print}->bounding_box;
+    @print_bb = (0,0,0,0) if !defined $print_bb[0];
+    $self->{shift} = [
+        ($self->{canvas}->GetSize->GetWidth  - ($self->to_pixel($print_bb[X2] + $print_bb[X1]))) / 2,
+        ($self->{canvas}->GetSize->GetHeight - ($self->to_pixel($print_bb[Y2] + $print_bb[Y1]))) / 2,
+    ];
+}
+
+sub repaint {
+    my ($self, $event) = @_;
+    my $parent = $self->GetParent;
+    my $print = $parent->{print};
+    
+    my $dc = Wx::PaintDC->new($self);
+    my $size = $self->GetSize;
+    my @size = ($size->GetWidth, $size->GetHeight);
+    
+    # draw grid
+    $dc->SetPen($parent->{grid_pen});
+    my $step = 10 * $parent->{scaling_factor};
+    for (my $x = $step; $x <= $size[X]; $x += $step) {
+        $dc->DrawLine($x, 0, $x, $size[Y]);
+    }
+    for (my $y = $step; $y <= $size[Y]; $y += $step) {
+        $dc->DrawLine(0, $y, $size[X], $y);
+    }
+    
+    # draw frame
+    $dc->SetPen(Wx::wxBLACK_PEN);
+    $dc->SetBrush($parent->{transparent_brush});
+    $dc->DrawRectangle(0, 0, @size);
+    
+    # draw text if plate is empty
+    if (!@{$print->objects}) {
+        $dc->SetTextForeground(Wx::Colour->new(150,50,50));
+        $dc->DrawLabel("Drag your objects here", Wx::Rect->new(0, 0, $self->GetSize->GetWidth, $self->GetSize->GetHeight), &Wx::wxALIGN_CENTER_HORIZONTAL | &Wx::wxALIGN_CENTER_VERTICAL);
+    }
+    
+    # draw thumbnails
+    $dc->SetPen(Wx::wxBLACK_PEN);
+    @{$parent->{object_previews}} = ();
+    for my $obj_idx (0 .. $#{$print->objects}) {
+        for my $copy_idx (0 .. $#{$print->copies->[$obj_idx]}) {
+            my $copy = $print->copies->[$obj_idx][$copy_idx];
+            push @{$parent->{object_previews}}, [ $obj_idx, $copy_idx, $parent->{thumbnails}[$obj_idx]->clone ];
+            $parent->{object_previews}->[-1][2]->translate(map $parent->to_pixel($copy->[$_]) + $parent->{shift}[$_], (X,Y));
+            
+            if (grep { $_->[0] == $obj_idx } @{$parent->{selected_objects}}) {
+                $dc->SetBrush($parent->{selected_brush});
+            } else {
+                $dc->SetBrush($parent->{objects_brush});
+            }
+            $dc->DrawPolygon($parent->_y($parent->{object_previews}->[-1][2]), 0, 0);
+        }
+    }
+    
+    # draw skirt
+    if (@{$parent->{object_previews}} && $Slic3r::skirts) {
+        my $convex_hull = Slic3r::Polygon->new(convex_hull([ map @{$_->[2]}, @{$parent->{object_previews}} ]));
+        $convex_hull = +($convex_hull->offset($Slic3r::skirt_distance * $parent->{scaling_factor}, 1))[0];
+        $dc->SetPen($parent->{skirt_pen});
+        $dc->SetBrush($parent->{transparent_brush});
+        $dc->DrawPolygon($parent->_y($convex_hull), 0, 0) if $convex_hull;
+    }
+    
+    $event->Skip;
+}
+
+sub mouse_event {
+    my ($self, $event) = @_;
+    my $parent = $self->GetParent;
+    my $print = $parent->{print};
+    
+    my $point = $event->GetPosition;
+    my $pos = $parent->_y([[$point->x, $point->y]])->[0]; #]]
+    if ($event->ButtonDown(&Wx::wxMOUSE_BTN_LEFT)) {
+        $parent->{selected_objects} = [];
+        $parent->{list}->Select($parent->{list}->GetFirstSelected, 0);
+        $parent->selection_changed(0);
+        for my $preview (@{$parent->{object_previews}}) {
+            if ($preview->[2]->encloses_point($pos)) {
+                $parent->{selected_objects} = [$preview];
+                $parent->{list}->Select($preview->[0], 1);
+                $parent->selection_changed(1);
+                my $copy = $print->copies->[ $preview->[0] ]->[ $preview->[1] ];
+                $self->{drag_start_pos} = [ map $pos->[$_] - $parent->{shift}[$_] - $parent->to_pixel($copy->[$_]), X,Y ];   # displacement between the click and the copy's origin
+                $self->{drag_object} = $preview;
+            }
+        }
+        $parent->Refresh;
+    } elsif ($event->ButtonUp(&Wx::wxMOUSE_BTN_LEFT)) {
+        $parent->recenter;
+        $parent->Refresh;
+        $self->{drag_start_pos} = undef;
+        $self->{drag_object} = undef;
+    } elsif ($event->Dragging) {
+        return if !$self->{drag_start_pos}; # concurrency problems
+        for my $obj ($self->{drag_object}) {
+            my $copy = $print->copies->[ $obj->[0] ]->[ $obj->[1] ];
+            $copy->[$_] = $parent->to_scaled($pos->[$_] - $self->{drag_start_pos}[$_] - $parent->{shift}[$_]) for X,Y;
+            $parent->Refresh;
+        }
+    }
+}
+
+sub list_item_deselected {
+    my ($self, $event) = @_;
+    
+    if ($self->{list}->GetFirstSelected == -1) {
+        $self->{selected_objects} = [];
+        $self->{canvas}->Refresh;
+        $self->selection_changed(0);
+    }
+}
+
+sub list_item_selected {
+    my ($self, $event) = @_;
+    
+    my $obj_idx = $event->GetIndex;
+    $self->{selected_objects} = [ grep $_->[0] == $obj_idx, @{$self->{object_previews}} ];
+    $self->{canvas}->Refresh;
+    $self->selection_changed(1);
+}
+
+sub object_list_changed {
+    my $self = shift;
+    
+    my $method = $self->{print} && @{$self->{print}->objects} ? 'Enable' : 'Disable';
+    $self->{$_}->$method
+        for qw(btn_reset btn_arrange btn_export_gcode);
+}
+
+sub selection_changed {
+    my $self = shift;
+    my ($have_sel) = @_;
+    
+    my $method = $have_sel ? 'Enable' : 'Disable';
+    $self->{$_}->$method
+        for qw(btn_remove btn_increase btn_decrease btn_rotate45cw btn_rotate45ccw btn_changescale);
+}
+
+sub selected_object_idx {
+    my $self = shift;
+    return $self->{selected_objects}[0][0] || $self->{list}->GetFirstSelected;
+}
+
+sub to_pixel {
+    my $self = shift;
+    return unscale $_[0] * $self->{scaling_factor};
+}
+
+sub to_scaled {
+    my $self = shift;
+    return scale $_[0] / $self->{scaling_factor};
+}
+
+sub _y {
+    my $self = shift;
+    my ($points) = @_;
+    my $height = $self->{canvas}->GetSize->GetHeight;
+    return [ map [ $_->[X], $height - $_->[Y] ], @$points ];
+}
+
+package Slic3r::GUI::Dashboard::DropTarget;
+
+use Wx::DND;
+use base 'Wx::FileDropTarget';
+
+sub new {
+    my $class = shift;
+    my ($window) = @_;
+    my $self = $class->SUPER::new;
+    $self->{window} = $window;
+    return $self;
+}
+
+sub OnDropFiles {
+    my $self = shift;
+    my ($x, $y, $filenames) = @_;
+    
+    # only accept STL and AMF files
+    return 0 if grep !/\.(?:stl|amf(?:\.xml)?)$/i, @$filenames;
+    
+    $self->{window}->load_file($_) for @$filenames;
+}
+
+1;
diff --git a/lib/Slic3r/GUI/OptionsGroup.pm b/lib/Slic3r/GUI/OptionsGroup.pm
index a695fe9bf..993117752 100644
--- a/lib/Slic3r/GUI/OptionsGroup.pm
+++ b/lib/Slic3r/GUI/OptionsGroup.pm
@@ -8,7 +8,7 @@ use base 'Wx::StaticBoxSizer';
 
 
 # not very elegant, but this solution is temporary waiting for a better GUI
-our @reload_callbacks = (\&update_duplicate_controls);
+our @reload_callbacks = ();
 our %fields = ();  # $key => [$control]
 
 sub new {
@@ -83,7 +83,6 @@ sub new {
             $field = Wx::Choice->new($parent, -1, Wx::wxDefaultPosition, Wx::wxDefaultSize, $opt->{labels} || $opt->{values});
             EVT_CHOICE($parent, $field, sub {
                 Slic3r::Config->set($opt_key, $opt->{values}[$field->GetSelection]);
-                update_duplicate_controls() if $opt_key eq 'duplicate_mode';
             });
             push @reload_callbacks, sub {
                 my $value = Slic3r::Config->get($opt_key);
@@ -102,19 +101,4 @@ sub new {
     return $self;
 }
 
-sub update_duplicate_controls {
-    # prevent infinite loops when calling ourselves
-    return if +(caller 1)[3] =~ /::update_duplicate_controls$/;
-    
-    my $value = Slic3r::Config->get('duplicate_mode');
-    $_->Enable($value eq 'autoarrange') for @{$fields{duplicate}};
-    $_->Enable($value eq 'autoarrange') for @{$fields{bed_size}};
-    $_->Enable($value eq 'grid') for @{$fields{duplicate_grid}};
-    $_->Enable($value ne 'no') for @{$fields{duplicate_distance}};
-    Slic3r::Config->set('duplicate', 1) if $value ne 'autoarrange';
-    Slic3r::Config->set('duplicate_grid', [1,1]) if $value ne 'grid';
-    $fields{duplicate}[0]->GetParent->Refresh;
-    $_->() for @reload_callbacks;  # apply new values
-}
-
 1;
diff --git a/lib/Slic3r/GUI/SkeinPanel.pm b/lib/Slic3r/GUI/SkeinPanel.pm
index 5f7eff210..f43312401 100644
--- a/lib/Slic3r/GUI/SkeinPanel.pm
+++ b/lib/Slic3r/GUI/SkeinPanel.pm
@@ -10,10 +10,10 @@ use Wx qw(:sizer :progressdialog wxOK wxICON_INFORMATION wxICON_WARNING wxICON_E
 use Wx::Event qw(EVT_BUTTON);
 use base 'Wx::Panel';
 
-my $last_skein_dir;
-my $last_config_dir;
-my $last_input_file;
-my $last_output_file;
+our $last_skein_dir;
+our $last_config_dir;
+our $last_input_file;
+our $last_output_file;
 our $last_config;
 
 sub new {
@@ -24,7 +24,7 @@ sub new {
     my %panels = (
         printer => {
             title => 'Printer',
-            options => [qw(nozzle_diameter print_center z_offset gcode_flavor use_relative_e_distances)],
+            options => [qw(nozzle_diameter bed_size print_center z_offset gcode_flavor use_relative_e_distances)],
         },
         filament => {
             title => 'Filament',
@@ -59,12 +59,8 @@ sub new {
             title => 'Skirt',
             options => [qw(skirts skirt_distance skirt_height)],
         },
-        transform => {
-            title => 'Transform',
-            options => [qw(scale rotate duplicate_mode duplicate bed_size duplicate_grid duplicate_distance)],
-        },
         gcode => {
-            title => 'Custom G-code',
+            title => 'G-code',
             options => [qw(start_gcode end_gcode layer_gcode gcode_comments post_process)],
         },
         extrusion => {
@@ -110,26 +106,25 @@ sub new {
     };
     
     my @tabs = (
-        $make_tab->([qw(transform accuracy skirt)], [qw(print retract)]),
+        $make_tab->([qw(accuracy skirt retract)], [qw(print notes)]),
         $make_tab->([qw(cooling)]),
         $make_tab->([qw(printer filament)], [qw(print_speed speed)]),
         $make_tab->([qw(gcode)]),
-        $make_tab->([qw(notes)]),
         $make_tab->([qw(extrusion)], [qw(output)]),
     );
     
+    $tabpanel->AddPage(Slic3r::GUI::Dashboard->new($tabpanel), "Dashboard");
     $tabpanel->AddPage($tabs[0], "Print Settings");
     $tabpanel->AddPage($tabs[1], "Cooling");
     $tabpanel->AddPage($tabs[2], "Printer and Filament");
-    $tabpanel->AddPage($tabs[3], "Custom G-code");
-    $tabpanel->AddPage($tabs[4], "Notes");
-    $tabpanel->AddPage($tabs[5], "Advanced");
+    $tabpanel->AddPage($tabs[3], "G-code");
+    $tabpanel->AddPage($tabs[4], "Advanced");
         
     my $buttons_sizer;
     {
         $buttons_sizer = Wx::BoxSizer->new(wxHORIZONTAL);
         
-        my $slice_button = Wx::Button->new($self, -1, "Slice...");
+        my $slice_button = Wx::Button->new($self, -1, "Quick slice…");
         $slice_button->SetDefault();
         $buttons_sizer->Add($slice_button, 0, wxRIGHT, 20);
         EVT_BUTTON($self, $slice_button, sub { $self->do_slice });
@@ -161,9 +156,9 @@ sub new {
     return $self;
 }
 
-my $model_wildcard = "STL files (*.stl)|*.stl;*.STL|AMF files (*.amf)|*.amf;*.AMF;*.xml;*.XML";
-my $ini_wildcard = "INI files *.ini|*.ini;*.INI";
-my $gcode_wildcard = "G-code files *.gcode|*.gcode;*.GCODE";
+our $model_wildcard = "STL files (*.stl)|*.stl;*.STL|AMF files (*.amf)|*.amf;*.AMF;*.xml;*.XML";
+our $ini_wildcard = "INI files *.ini|*.ini;*.INI";
+our $gcode_wildcard = "G-code files *.gcode|*.gcode;*.GCODE";
 
 sub do_slice {
     my $self = shift;
@@ -212,24 +207,15 @@ sub do_slice {
         my $input_file_basename = basename($input_file);
         $last_skein_dir = dirname($input_file);
         
-        my $skein = Slic3r::Skein->new(
-            input_file  => $input_file,
-            output_file => $main::opt{output},
-            status_cb   => sub {
-                my ($percent, $message) = @_;
-                if (&Wx::wxVERSION_STRING =~ / 2\.(8\.|9\.[2-9])/) {
-                    $process_dialog->Update($percent, "$message...");
-                }
-            },
-        );
+        my $print = Slic3r::Print->new;
+        $print->add_object_from_file($input_file);
 
         # select output file
+        my $output_file = $main::opt{output};
         if ($params{reslice}) {
-            if (defined $last_output_file) {
-                $skein->output_file($last_output_file);
-            }
+            $output_file = $last_output_file if defined $last_output_file;
         } elsif ($params{save_as}) {
-            my $output_file = $skein->expanded_output_filepath;
+            $output_file = $print->expanded_output_filepath($output_file);
             $output_file =~ s/\.gcode$/.svg/i if $params{export_svg};
             my $dlg = Wx::FileDialog->new($self, 'Save ' . ($params{export_svg} ? 'SVG' : 'G-code') . ' file as:', dirname($output_file),
                 basename($output_file), $gcode_wildcard, wxFD_SAVE);
@@ -237,8 +223,7 @@ sub do_slice {
                 $dlg->Destroy;
                 return;
             }
-            $skein->output_file($dlg->GetPath);
-            $last_output_file = $dlg->GetPath;
+            $output_file = $last_output_file = $dlg->GetPath;
             $dlg->Destroy;
         }
         
@@ -250,21 +235,30 @@ sub do_slice {
         {
             my @warnings = ();
             local $SIG{__WARN__} = sub { push @warnings, $_[0] };
+            my %params = (
+                output_file => $output_file,
+                status_cb   => sub {
+                    my ($percent, $message) = @_;
+                    if (&Wx::wxVERSION_STRING =~ / 2\.(8\.|9\.[2-9])/) {
+                        $process_dialog->Update($percent, "$message...");
+                    }
+                },
+            );
             if ($params{export_svg}) {
-                $skein->export_svg;
+                $print->export_svg(%params);
             } else {
-                $skein->go;
+                $print->export_gcode(%params);
             }
-            $self->catch_warning->($_) for @warnings;
+            Slic3r::GUI::warning_catcher($self)->($_) for @warnings;
         }
         $process_dialog->Destroy;
         undef $process_dialog;
         
         my $message = "$input_file_basename was successfully sliced";
         $message .= sprintf " in %d minutes and %.3f seconds",
-            int($skein->processing_time/60),
-            $skein->processing_time - int($skein->processing_time/60)*60
-            if $skein->processing_time;
+            int($print->processing_time/60),
+            $print->processing_time - int($print->processing_time/60)*60
+                if $print->processing_time;
         $message .= ".";
         eval {
             $self->{growler}->notify(Event => 'SKEIN_DONE', Title => 'Slicing Done!', Message => $message)
@@ -273,7 +267,7 @@ sub do_slice {
         Wx::MessageDialog->new($self, $message, 'Done!', 
             wxOK | wxICON_INFORMATION)->ShowModal;
     };
-    $self->catch_error(sub { $process_dialog->Destroy if $process_dialog });
+    Slic3r::GUI::catch_error($self, sub { $process_dialog->Destroy if $process_dialog });
 }
 
 sub save_config {
@@ -284,7 +278,7 @@ sub save_config {
         # validate configuration
         Slic3r::Config->validate;
     };
-    $self->catch_error(sub { $process_dialog->Destroy if $process_dialog }) and return;
+    Slic3r::GUI::catch_error($self, sub { $process_dialog->Destroy if $process_dialog }) and return;
     
     my $dir = $last_config ? dirname($last_config) : $last_config_dir || $last_skein_dir || "";
     my $filename = $last_config ? basename($last_config) : "config.ini";
@@ -310,7 +304,7 @@ sub load_config {
         $last_config_dir = dirname($file);
         $last_config = $file;
         eval {
-            local $SIG{__WARN__} = $self->catch_warning;
+            local $SIG{__WARN__} = Slic3r::GUI::warning_catcher($self);
             Slic3r::Config->load($file);
         };
         $self->catch_error();
@@ -319,22 +313,4 @@ sub load_config {
     $dlg->Destroy;
 }
 
-sub catch_error {
-    my ($self, $cb) = @_;
-    if (my $err = $@) {
-        $cb->() if $cb;
-        Wx::MessageDialog->new($self, $err, 'Error', wxOK | wxICON_ERROR)->ShowModal;
-        return 1;
-    }
-    return 0;
-}
-
-sub catch_warning {
-    my ($self) = @_;
-    return sub {
-        my $message = shift;
-        Wx::MessageDialog->new($self, $message, 'Warning', wxOK | wxICON_WARNING)->ShowModal;
-    };
-};
-
 1;
diff --git a/lib/Slic3r/Geometry.pm b/lib/Slic3r/Geometry.pm
index 7a30499b4..304a0fecf 100644
--- a/lib/Slic3r/Geometry.pm
+++ b/lib/Slic3r/Geometry.pm
@@ -875,4 +875,112 @@ sub douglas_peucker2 {
     return [ map $points->[$_], sort keys %keep ];
 }
 
+sub arrange {
+    my ($total_parts, $partx, $party, $areax, $areay, $dist) = @_;
+    
+    my $linint = sub {
+        my ($value, $oldmin, $oldmax, $newmin, $newmax) = @_;
+        return ($value - $oldmin) * ($newmax - $newmin) / ($oldmax - $oldmin) + $newmin;
+    };
+    
+    # use actual part size (the largest) plus separation distance (half on each side) in spacing algorithm
+    $partx += $dist;
+    $party += $dist;
+    
+    # margin needed for the skirt
+    my $skirt_margin;		
+    if ($Slic3r::skirts > 0) {
+        $skirt_margin = ($Slic3r::flow_spacing * $Slic3r::skirts + $Slic3r::skirt_distance) * 2;
+    } else {
+        $skirt_margin = 0;		
+    }
+    
+    # this is how many cells we have available into which to put parts
+    my $cellw = int(($areax - $skirt_margin + $dist) / $partx);
+    my $cellh = int(($areay - $skirt_margin + $dist) / $party);
+    
+    die "$total_parts parts won't fit in your print area!\n" if $total_parts > ($cellw * $cellh);
+    
+    # width and height of space used by cells
+    my $w = $cellw * $partx;
+    my $h = $cellh * $party;
+    
+    # left and right border positions of space used by cells
+    my $l = ($areax - $w) / 2;
+    my $r = $l + $w;
+    
+    # top and bottom border positions
+    my $t = ($areay - $h) / 2;
+    my $b = $t + $h;
+    
+    # list of cells, sorted by distance from center
+    my @cellsorder;
+    
+    # work out distance for all cells, sort into list
+    for my $i (0..$cellw-1) {
+        for my $j (0..$cellh-1) {
+            my $cx = $linint->($i + 0.5, 0, $cellw, $l, $r);
+            my $cy = $linint->($j + 0.5, 0, $cellh, $t, $b);
+            
+            my $xd = abs(($areax / 2) - $cx);
+            my $yd = abs(($areay / 2) - $cy);
+            
+            my $c = {
+                location => [$cx, $cy],
+                index => [$i, $j],
+                distance => $xd * $xd + $yd * $yd - abs(($cellw / 2) - ($i + 0.5)),
+            };
+            
+            BINARYINSERTIONSORT: {
+                my $index = $c->{distance};
+                my $low = 0;
+                my $high = @cellsorder;
+                while ($low < $high) {
+                    my $mid = ($low + (($high - $low) / 2)) | 0;
+                    my $midval = $cellsorder[$mid]->[0];
+                    
+                    if ($midval < $index) {
+                        $low = $mid + 1;
+                    } elsif ($midval > $index) {
+                        $high = $mid;
+                    } else {
+                        splice @cellsorder, $mid, 0, [$index, $c];
+                        last BINARYINSERTIONSORT;
+                    }
+                }
+                splice @cellsorder, $low, 0, [$index, $c];
+            }
+        }
+    }
+    
+    # the extents of cells actually used by objects
+    my ($lx, $ty, $rx, $by) = (0, 0, 0, 0);
+
+    # now find cells actually used by objects, map out the extents so we can position correctly
+    for my $i (1..$total_parts) {
+        my $c = $cellsorder[$i - 1];
+        my $cx = $c->[1]->{index}->[0];
+        my $cy = $c->[1]->{index}->[1];
+        if ($i == 1) {
+            $lx = $rx = $cx;
+            $ty = $by = $cy;
+        } else {
+            $rx = $cx if $cx > $rx;
+            $lx = $cx if $cx < $lx;
+            $by = $cy if $cy > $by;
+            $ty = $cy if $cy < $ty;
+        }
+    }
+    # now we actually place objects into cells, positioned such that the left and bottom borders are at 0
+    my @positions = ();
+    for (1..$total_parts) {
+        my $c = shift @cellsorder;
+        my $cx = $c->[1]->{index}->[0] - $lx;
+        my $cy = $c->[1]->{index}->[1] - $ty;
+
+        push @positions, [$cx * $partx, $cy * $party];
+    }
+    return @positions;
+}
+
 1;
diff --git a/lib/Slic3r/Print.pm b/lib/Slic3r/Print.pm
index e3faa9bb9..b6970d973 100644
--- a/lib/Slic3r/Print.pm
+++ b/lib/Slic3r/Print.pm
@@ -1,15 +1,16 @@
 package Slic3r::Print;
 use Moo;
 
+use File::Basename qw(basename fileparse);
 use Math::ConvexHull 1.0.4 qw(convex_hull);
-use Slic3r::Geometry qw(X Y Z PI scale unscale move_points);
+use Slic3r::Geometry qw(X Y Z X1 Y1 X2 Y2 PI scale unscale move_points);
 use Slic3r::Geometry::Clipper qw(diff_ex union_ex offset JT_ROUND);
+use Time::HiRes qw(gettimeofday tv_interval);
 
-has 'objects'           => (is => 'rw', default => sub {[]});
-has 'copies'            => (is => 'rw', default => sub {[]});  # obj_idx => [copies...]
-has 'total_x_length'    => (is => 'rw'); # including duplicates
-has 'total_y_length'    => (is => 'rw'); # including duplicates
+has 'objects'                => (is => 'rw', default => sub {[]});
+has 'copies'                 => (is => 'rw', default => sub {[]});  # obj_idx => [copies...]
 has 'total_extrusion_length' => (is => 'rw');
+has 'processing_time'        => (is => 'rw', required => 0);
 
 # ordered collection of extrusion paths to build skirt loops
 has 'skirt' => (
@@ -18,6 +19,26 @@ has 'skirt' => (
     default => sub { [] },
 );
 
+sub add_object_from_file {
+    my $self = shift;
+    my ($input_file) = @_;
+    
+    my $object;
+    if ($input_file =~ /\.stl$/i) {
+        my $mesh = Slic3r::Format::STL->read_file($input_file);
+        $mesh->check_manifoldness;
+        $object = $self->add_object_from_mesh($mesh);
+    } elsif ( $input_file =~ /\.amf(\.xml)?$/i) {
+        my ($materials, $meshes_by_material) = Slic3r::Format::AMF->read_file($input_file);
+        $_->check_manifoldness for values %$meshes_by_material;
+        $object = $self->add_object_from_mesh($meshes_by_material->{_} || +(values %$meshes_by_material)[0]);
+    } else {
+        die "Input file must have .stl or .amf(.xml) extension\n";
+    }
+    $object->input_file($input_file);
+    return $object;
+}
+
 sub add_object_from_mesh {
     my $self = shift;
     my ($mesh) = @_;
@@ -29,123 +50,13 @@ sub add_object_from_mesh {
     # initialize print object
     my @size = $mesh->size;
     my $object = Slic3r::Print::Object->new(
+        mesh     => $mesh,
         x_length => $size[X],
         y_length => $size[Y],
     );
     
-    # process facets
-    {
-        my $apply_lines = sub {
-            my $lines = shift;
-            foreach my $layer_id (keys %$lines) {
-                my $layer = $object->layer($layer_id);
-                $layer->add_line($_) for @{ $lines->{$layer_id} };
-            }
-        };
-        Slic3r::parallelize(
-            disable => ($#{$mesh->facets} < 500),  # don't parallelize when too few facets
-            items => [ 0..$#{$mesh->facets} ],
-            thread_cb => sub {
-                my $q = shift;
-                my $result_lines = {};
-                while (defined (my $facet_id = $q->dequeue)) {
-                    my $lines = $mesh->slice_facet($object, $facet_id);
-                    foreach my $layer_id (keys %$lines) {
-                        $result_lines->{$layer_id} ||= [];
-                        push @{ $result_lines->{$layer_id} }, @{ $lines->{$layer_id} };
-                    }
-                }
-                return $result_lines;
-            },
-            collect_cb => sub {
-                $apply_lines->($_[0]);
-            },
-            no_threads_cb => sub {
-                for (0..$#{$mesh->facets}) {
-                    my $lines = $mesh->slice_facet($object, $_);
-                    $apply_lines->($lines);
-                }
-            },
-        );
-    }
-    die "Invalid input file\n" if !@{$object->layers};
-    
-    # remove last layer if empty
-    # (we might have created it because of the $max_layer = ... + 1 code below)
-    pop @{$object->layers} if !@{$object->layers->[-1]->surfaces} && !@{$object->layers->[-1]->lines};
-    
-    foreach my $layer (@{ $object->layers }) {
-        Slic3r::debugf "Making surfaces for layer %d (slice z = %f):\n",
-            $layer->id, unscale $layer->slice_z if $Slic3r::debug;
-        
-        # layer currently has many lines representing intersections of
-        # model facets with the layer plane. there may also be lines
-        # that we need to ignore (for example, when two non-horizontal
-        # facets share a common edge on our plane, we get a single line;
-        # however that line has no meaning for our layer as it's enclosed
-        # inside a closed polyline)
-        
-        # build surfaces from sparse lines
-        $layer->make_surfaces($mesh->make_loops($layer));
-        
-        # free memory
-        $layer->lines(undef);
-    }
-    
-    # detect slicing errors
-    my $warning_thrown = 0;
-    for my $i (0 .. $#{$object->layers}) {
-        my $layer = $object->layers->[$i];
-        next unless $layer->slicing_errors;
-        if (!$warning_thrown) {
-            warn "The model has overlapping or self-intersecting facets. I tried to repair it, "
-                . "however you might want to check the results or repair the input file and retry.\n";
-            $warning_thrown = 1;
-        }
-        
-        # try to repair the layer surfaces by merging all contours and all holes from
-        # neighbor layers
-        Slic3r::debugf "Attempting to repair layer %d\n", $i;
-        
-        my (@upper_surfaces, @lower_surfaces);
-        for (my $j = $i+1; $j <= $#{$object->layers}; $j++) {
-            if (!$object->layers->[$j]->slicing_errors) {
-                @upper_surfaces = @{$object->layers->[$j]->slices};
-                last;
-            }
-        }
-        for (my $j = $i-1; $j >= 0; $j--) {
-            if (!$object->layers->[$j]->slicing_errors) {
-                @lower_surfaces = @{$object->layers->[$j]->slices};
-                last;
-            }
-        }
-        
-        my $union = union_ex([
-            map $_->expolygon->contour, @upper_surfaces, @lower_surfaces,
-        ]);
-        my $diff = diff_ex(
-            [ map @$_, @$union ],
-            [ map $_->expolygon->holes, @upper_surfaces, @lower_surfaces, ],
-        );
-        
-        @{$layer->slices} = map Slic3r::Surface->new
-            (expolygon => $_, surface_type => 'internal'),
-            @$diff;
-    }
-    
-    # remove empty layers from bottom
-    while (@{$object->layers} && !@{$object->layers->[0]->slices} && !@{$object->layers->[0]->thin_walls}) {
-        shift @{$object->layers};
-        for (my $i = 0; $i <= $#{$object->layers}; $i++) {
-            $object->layers->[$i]->id($i);
-        }
-    }
-    
-    warn "No layers were detected. You might want to repair your STL file and retry.\n"
-        if !@{$object->layers};
-    
     push @{$self->objects}, $object;
+    push @{$self->copies}, [[0, 0]];
     return $object;
 }
 
@@ -158,21 +69,18 @@ sub layer_count {
     return $count;
 }
 
-sub arrange_objects {
+sub duplicate {
     my $self = shift;
     
-    my $dist = scale $Slic3r::duplicate_distance;
-
     if ($Slic3r::duplicate_grid->[X] > 1 || $Slic3r::duplicate_grid->[Y] > 1) {
         if (@{$self->objects} > 1) {
             die "Grid duplication is not supported with multiple objects\n";
         }
         my $object = $self->objects->[0];
-        $self->total_x_length($object->x_length * $Slic3r::duplicate_grid->[X] + $dist * ($Slic3r::duplicate_grid->[X] - 1));
-        $self->total_y_length($object->y_length * $Slic3r::duplicate_grid->[Y] + $dist * ($Slic3r::duplicate_grid->[Y] - 1));
         
         # generate offsets for copies
-        push @{$self->copies}, [];
+        my $dist = scale $Slic3r::duplicate_distance;
+        @{$self->copies->[0]} = ();
         for my $x_copy (1..$Slic3r::duplicate_grid->[X]) {
             for my $y_copy (1..$Slic3r::duplicate_grid->[Y]) {
                 push @{$self->copies->[0]}, [
@@ -181,132 +89,247 @@ sub arrange_objects {
                 ];
             }
         }
-    } elsif ($Slic3r::duplicate > 1 || @{$self->objects} > 1) {
-        my $total_parts = @{$self->objects} * $Slic3r::duplicate;
-        my $linint = sub {
-            my ($value, $oldmin, $oldmax, $newmin, $newmax) = @_;
-            return ($value - $oldmin) * ($newmax - $newmin) / ($oldmax - $oldmin) + $newmin;
-        };
-
-        # use actual part size (the largest) plus separation distance (half on each side) in spacing algorithm
-        my $partx = my $party = 0;
-        foreach my $object (@{$self->objects}) {
-            $partx = $object->x_length if $object->x_length > $partx;
-            $party = $object->y_length if $object->y_length > $party;
+    } elsif ($Slic3r::duplicate > 1) {
+        foreach my $copies (@{$self->copies}) {
+            @$copies = map [0,0], 1..$Slic3r::duplicate;
         }
-        $partx = unscale($partx) + $Slic3r::duplicate_distance;
-        $party = unscale($party) + $Slic3r::duplicate_distance;
-
-        # margin needed for the skirt
-        my $skirt_margin;		
-        if ($Slic3r::skirts > 0) {
-            $skirt_margin = ($Slic3r::flow_spacing * $Slic3r::skirts + $Slic3r::skirt_distance) * 2;
-        } else {
-            $skirt_margin = 0;		
-        }
-
-        # this is how many cells we have available into which to put parts
-        my $cellw = int(($Slic3r::bed_size->[X] - $skirt_margin + $Slic3r::duplicate_distance) / $partx);
-        my $cellh = int(($Slic3r::bed_size->[Y] - $skirt_margin + $Slic3r::duplicate_distance) / $party);
-
-        die "$total_parts parts won't fit in your print area!\n" if $total_parts > ($cellw * $cellh);
-
-        # width and height of space used by cells
-        my $w = $cellw * $partx;
-        my $h = $cellh * $party;
-
-        # left and right border positions of space used by cells
-        my $l = ($Slic3r::bed_size->[X] - $w) / 2;
-        my $r = $l + $w;
-
-        # top and bottom border positions
-        my $t = ($Slic3r::bed_size->[Y] - $h) / 2;
-        my $b = $t + $h;
-
-        # list of cells, sorted by distance from center
-        my @cellsorder;
-
-        # work out distance for all cells, sort into list
-        for my $i (0..$cellw-1) {
-            for my $j (0..$cellh-1) {
-                my $cx = $linint->($i + 0.5, 0, $cellw, $l, $r);
-                my $cy = $linint->($j + 0.5, 0, $cellh, $t, $b);
-
-                my $xd = abs(($Slic3r::bed_size->[X] / 2) - $cx);
-                my $yd = abs(($Slic3r::bed_size->[Y] / 2) - $cy);
-
-                my $c = {
-                    location => [$cx, $cy],
-                    index => [$i, $j],
-                    distance => $xd * $xd + $yd * $yd - abs(($cellw / 2) - ($i + 0.5)),
-                };
-
-                BINARYINSERTIONSORT: {
-                    my $index = $c->{distance};
-                    my $low = 0;
-                    my $high = @cellsorder;
-                    while ($low < $high) {
-                        my $mid = ($low + (($high - $low) / 2)) | 0;
-                        my $midval = $cellsorder[$mid]->[0];
-        
-                        if ($midval < $index) {
-                            $low = $mid + 1;
-                        } elsif ($midval > $index) {
-                            $high = $mid;
-                        } else {
-                            splice @cellsorder, $mid, 0, [$index, $c];
-                            last BINARYINSERTIONSORT;
-                        }
-                    }
-                    splice @cellsorder, $low, 0, [$index, $c];
-                }
-            }
-        }
-
-        # the extents of cells actually used by objects
-        my ($lx, $ty, $rx, $by) = (0, 0, 0, 0);
-
-        # now find cells actually used by objects, map out the extents so we can position correctly
-        for my $i (1..$total_parts) {
-            my $c = $cellsorder[$i - 1];
-            my $cx = $c->[1]->{index}->[0];
-            my $cy = $c->[1]->{index}->[1];
-            if ($i == 1) {
-                $lx = $rx = $cx;
-                $ty = $by = $cy;
-            } else {
-                $rx = $cx if $cx > $rx;
-                $lx = $cx if $cx < $lx;
-                $by = $cy if $cy > $by;
-                $ty = $cy if $cy < $ty;
-            }
-        }
-        # now we actually place objects into cells, positioned such that the left and bottom borders are at 0
-        for (0..$#{$self->objects}) {
-            my @copies = ();
-            for (1..$Slic3r::duplicate) {
-                my $c = shift @cellsorder;
-                my $cx = $c->[1]->{index}->[0] - $lx;
-                my $cy = $c->[1]->{index}->[1] - $ty;
-    
-                push @copies, [scale($cx * $partx), scale($cy * $party)];
-            }
-            push @{$self->copies}, [@copies];
-        }
-
-        # save size of area used
-        $self->total_x_length(scale(($rx - $lx + 1) * $partx - $Slic3r::duplicate_distance));
-        $self->total_y_length(scale(($by - $ty + 1) * $party - $Slic3r::duplicate_distance));
-    } else {
-        $self->total_x_length($self->objects->[0]->x_length);
-        $self->total_y_length($self->objects->[0]->y_length);
-        push @{$self->copies}, [[0, 0]];
+        $self->arrange_objects;
     }
 }
 
-sub max_length {
+sub arrange_objects {
     my $self = shift;
-    return ($self->total_x_length > $self->total_y_length) ? $self->total_x_length : $self->total_y_length;
+
+    my $total_parts = scalar map @$_, @{$self->copies};
+    my $partx = my $party = 0;
+    foreach my $object (@{$self->objects}) {
+        $partx = $object->x_length if $object->x_length > $partx;
+        $party = $object->y_length if $object->y_length > $party;
+    }
+    my @positions = Slic3r::Geometry::arrange
+        ($total_parts, $partx, $party, (map scale $_, @$Slic3r::bed_size), scale $Slic3r::duplicate_distance);
+    
+    for my $obj_idx (0..$#{$self->objects}) {
+        @{$self->copies->[$obj_idx]} = splice @positions, 0, scalar @{$self->copies->[$obj_idx]};
+    }
+}
+
+sub bounding_box {
+    my $self = shift;
+    
+    my @points = ();
+    foreach my $obj_idx (0 .. $#{$self->objects}) {
+        my $object = $self->objects->[$obj_idx];
+        foreach my $copy (@{$self->copies->[$obj_idx]}) {
+            push @points,
+                [ $copy->[X], $copy->[Y] ],
+                [ $copy->[X] + $object->x_length, $copy->[Y] ],
+                [ $copy->[X] + $object->x_length, $copy->[Y] + $object->y_length ],
+                [ $copy->[X], $copy->[Y] + $object->y_length ];
+        }
+    }
+    return Slic3r::Geometry::bounding_box(\@points);
+}
+
+sub size {
+    my $self = shift;
+    
+    my @bb = $self->bounding_box;
+    return [ $bb[X2] - $bb[X1], $bb[Y2] - $bb[Y1] ];
+}
+
+sub export_gcode {
+    my $self = shift;
+    my %params = @_;
+    
+    my $status_cb = $params{status_cb} || sub {};
+    my $t0 = [gettimeofday];
+    
+    # skein the STL into layers
+    # each layer has surfaces with holes
+    $status_cb->(5, "Processing input file");    
+    $status_cb->(10, "Processing triangulated mesh");
+    $_->slice for @{$self->objects};
+    unless ($params{keep_meshes}) {
+        $_->mesh(undef) for @{$self->objects};  # free memory
+    }
+    
+    # make perimeters
+    # this will add a set of extrusion loops to each layer
+    # as well as generate infill boundaries
+    $status_cb->(20, "Generating perimeters");
+    $_->make_perimeters for map @{$_->layers}, @{$self->objects};
+    
+    # this will clip $layer->surfaces to the infill boundaries 
+    # and split them in top/bottom/internal surfaces;
+    $status_cb->(30, "Detecting solid surfaces");
+    $_->detect_surfaces_type for @{$self->objects};
+    
+    # decide what surfaces are to be filled
+    $status_cb->(35, "Preparing infill surfaces");
+    $_->prepare_fill_surfaces for map @{$_->layers}, @{$self->objects};
+    
+    # this will remove unprintable surfaces
+    # (those that are too tight for extrusion)
+    $status_cb->(40, "Cleaning up");
+    $_->remove_small_surfaces for map @{$_->layers}, @{$self->objects};
+    
+    # this will detect bridges and reverse bridges
+    # and rearrange top/bottom/internal surfaces
+    $status_cb->(45, "Detect bridges");
+    $_->process_bridges for map @{$_->layers}, @{$self->objects};
+    
+    # this will remove unprintable perimeter loops
+    # (those that are too tight for extrusion)
+    $status_cb->(50, "Cleaning up the perimeters");
+    $_->remove_small_perimeters for map @{$_->layers}, @{$self->objects};
+    
+    # detect which fill surfaces are near external layers
+    # they will be split in internal and internal-solid surfaces
+    $status_cb->(60, "Generating horizontal shells");
+    $_->discover_horizontal_shells for @{$self->objects};
+    
+    # free memory
+    @{$_->surfaces} = () for map @{$_->layers}, @{$self->objects};
+    
+    # combine fill surfaces to honor the "infill every N layers" option
+    $status_cb->(70, "Combining infill");
+    $_->infill_every_layers for @{$self->objects};
+    
+    # this will generate extrusion paths for each layer
+    $status_cb->(80, "Infilling layers");
+    {
+        my $fill_maker = Slic3r::Fill->new('print' => $self);
+        
+        my @items = ();  # [obj_idx, layer_id]
+        foreach my $obj_idx (0 .. $#{$self->objects}) {
+            push @items, map [$obj_idx, $_], 0..$#{$self->objects->[$obj_idx]->layers};
+        }
+        Slic3r::parallelize(
+            items => [@items],
+            thread_cb => sub {
+                my $q = shift;
+                $Slic3r::Geometry::Clipper::clipper = Math::Clipper->new;
+                my $fills = {};
+                while (defined (my $obj_layer = $q->dequeue)) {
+                    my ($obj_idx, $layer_id) = @$obj_layer;
+                    $fills->{$obj_idx} ||= {};
+                    $fills->{$obj_idx}{$layer_id} = [ $fill_maker->make_fill($self->objects->[$obj_idx]->layers->[$layer_id]) ];
+                }
+                return $fills;
+            },
+            collect_cb => sub {
+                my $fills = shift;
+                foreach my $obj_idx (keys %$fills) {
+                    foreach my $layer_id (keys %{$fills->{$obj_idx}}) {
+                        @{$self->objects->[$obj_idx]->layers->[$layer_id]->fills} = @{$fills->{$obj_idx}{$layer_id}};
+                    }
+                }
+            },
+            no_threads_cb => sub {
+                foreach my $layer (map @{$_->layers}, @{$self->objects}) {
+                    @{$layer->fills} = $fill_maker->make_fill($layer);
+                }
+            },
+        );
+    }
+    
+    # generate support material
+    if ($Slic3r::support_material) {
+        $status_cb->(85, "Generating support material");
+        $_->generate_support_material for @{$self->objects};
+    }
+    
+    # free memory (note that support material needs fill_surfaces)
+    @{$_->fill_surfaces} = () for map @{$_->layers}, @{$self->objects};
+    
+    # make skirt
+    $status_cb->(88, "Generating skirt");
+    $self->make_skirt;
+    
+    # output everything to a G-code file
+    my $output_file = $self->expanded_output_filepath($params{output_file});
+    $status_cb->(90, "Exporting G-code to $output_file");
+    $self->write_gcode($output_file);
+    
+    # run post-processing scripts
+    if (@$Slic3r::post_process) {
+        $status_cb->(95, "Running post-processing scripts");
+        for (@$Slic3r::post_process) {
+            Slic3r::debugf "  '%s' '%s'\n", $_, $output_file;
+            system($_, $output_file);
+        }
+    }
+    
+    # output some statistics
+    $self->processing_time(tv_interval($t0));
+    printf "Done. Process took %d minutes and %.3f seconds\n", 
+        int($self->processing_time/60),
+        $self->processing_time - int($self->processing_time/60)*60;
+    
+    # TODO: more statistics!
+    printf "Filament required: %.1fmm (%.1fcm3)\n",
+        $self->total_extrusion_length, $self->total_extrusion_volume;
+}
+
+sub export_svg {
+    my $self = shift;
+    my %params = @_;
+    
+    $_->slice for @{$self->objects};
+    unless ($params{keep_meshes}) {
+        $_->mesh(undef) for @{$self->objects};  # free memory
+    }
+    $self->arrange_objects;
+    
+    my $output_file = $self->expanded_output_filepath($params{output_file});
+    $output_file =~ s/\.gcode$/.svg/i;
+    
+    open my $fh, ">", $output_file or die "Failed to open $output_file for writing\n";
+    print "Exporting to $output_file...";
+    my $print_size = $self->size;
+    print $fh sprintf <<"EOF", unscale($print_size->[X]), unscale($print_size->[Y]);
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.0//EN" "http://www.w3.org/TR/2001/REC-SVG-20010904/DTD/svg10.dtd">
+<svg width="%s" height="%s" xmlns="http://www.w3.org/2000/svg" xmlns:svg="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:slic3r="http://slic3r.org/namespaces/slic3r">
+  <!-- 
+  Generated using Slic3r $Slic3r::VERSION
+  http://slic3r.org/
+   -->
+EOF
+    
+    my $print_polygon = sub {
+        my ($polygon, $type) = @_;
+        printf $fh qq{    <polygon slic3r:type="%s" points="%s" style="fill: %s" />\n},
+            $type, (join ' ', map { join ',', map unscale $_, @$_ } @$polygon),
+            ($type eq 'contour' ? 'black' : 'white');
+    };
+    
+    for my $layer_id (0..$self->layer_count-1) {
+        my @layers = map $_->layers->[$layer_id], @{$self->objects};
+        printf $fh qq{  <g id="layer%d" slic3r:z="%s">\n}, $layer_id, unscale +(grep defined $_, @layers)[0]->slice_z;
+        
+        for my $obj_idx (0 .. $#layers) {
+            my $layer = $layers[$layer_id] or next;
+            
+            # sort slices so that the outermost ones come first
+            my @slices = sort { $a->expolygon->contour->encloses_point($b->expolygon->contour->[0]) ? 0 : 1 } @{$layer->slices};
+            
+            foreach my $copy (@{$self->copies->[$obj_idx]}) {
+                foreach my $slice (@slices) {
+                    my $expolygon = $slice->expolygon->clone;
+                    $expolygon->translate(@$copy);
+                    $print_polygon->($expolygon->contour, 'contour');
+                    $print_polygon->($_, 'hole') for $expolygon->holes;
+                }
+            }
+        }
+        print $fh qq{  </g>\n};
+    }
+    
+    print $fh "</svg>\n";
+    close $fh;
+    print "Done.\n";
 }
 
 sub make_skirt {
@@ -344,7 +367,7 @@ sub make_skirt {
     push @{$self->skirt}, @skirt;
 }
 
-sub export_gcode {
+sub write_gcode {
     my $self = shift;
     my ($file) = @_;
     
@@ -394,9 +417,10 @@ sub export_gcode {
     }
     
     # calculate X,Y shift to center print around specified origin
+    my @print_bb = $self->bounding_box;
     my @shift = (
-        $Slic3r::print_center->[X] - (unscale $self->total_x_length / 2),
-        $Slic3r::print_center->[Y] - (unscale $self->total_y_length / 2),
+        $Slic3r::print_center->[X] - (unscale ($print_bb[X2] - $print_bb[X1]) / 2) - unscale $print_bb[X1],
+        $Slic3r::print_center->[Y] - (unscale ($print_bb[Y2] - $print_bb[Y1]) / 2) - unscale $print_bb[Y1],
     );
     
     # set up our extruder object
@@ -523,4 +547,24 @@ sub total_extrusion_volume {
     return $self->total_extrusion_length * ($Slic3r::filament_diameter**2) * PI/4 / 1000;
 }
 
+# this method will return the value of $self->output_file after expanding its
+# format variables with their values
+sub expanded_output_filepath {
+    my $self = shift;
+    my ($path) = @_;
+    
+    # if no explicit output file was defined, we take the input
+    # file directory and append the specified filename format
+    my $input_file = $self->objects->[0]->input_file;
+    $path ||= (fileparse($input_file))[1] . $Slic3r::output_filename_format;
+    
+    my $input_filename = my $input_filename_base = basename($input_file);
+    $input_filename_base =~ s/\.(?:stl|amf(?:\.xml)?)$//i;
+    
+    return Slic3r::Config->replace_options($path, {
+        input_filename      => $input_filename,
+        input_filename_base => $input_filename_base,
+    });
+}
+
 1;
diff --git a/lib/Slic3r/Print/Object.pm b/lib/Slic3r/Print/Object.pm
index e280b8d37..2784acc8f 100644
--- a/lib/Slic3r/Print/Object.pm
+++ b/lib/Slic3r/Print/Object.pm
@@ -4,8 +4,10 @@ use Moo;
 use Slic3r::Geometry qw(scale);
 use Slic3r::Geometry::Clipper qw(diff_ex intersection_ex union_ex);
 
-has 'x_length'          => (is => 'ro', required => 1);
-has 'y_length'          => (is => 'ro', required => 1);
+has 'input_file'        => (is => 'rw', required => 0);
+has 'mesh'              => (is => 'rw', required => 0);
+has 'x_length'          => (is => 'rw', required => 1);
+has 'y_length'          => (is => 'rw', required => 1);
 
 has 'layers' => (
     traits  => ['Array'],
@@ -34,6 +36,122 @@ sub layer {
     return $self->layers->[$layer_id];
 }
 
+sub slice {
+    my $self = shift;
+    
+    # process facets
+    {
+        my $apply_lines = sub {
+            my $lines = shift;
+            foreach my $layer_id (keys %$lines) {
+                my $layer = $self->layer($layer_id);
+                $layer->add_line($_) for @{ $lines->{$layer_id} };
+            }
+        };
+        Slic3r::parallelize(
+            disable => ($#{$self->mesh->facets} < 500),  # don't parallelize when too few facets
+            items => [ 0..$#{$self->mesh->facets} ],
+            thread_cb => sub {
+                my $q = shift;
+                my $result_lines = {};
+                while (defined (my $facet_id = $q->dequeue)) {
+                    my $lines = $self->mesh->slice_facet($self, $facet_id);
+                    foreach my $layer_id (keys %$lines) {
+                        $result_lines->{$layer_id} ||= [];
+                        push @{ $result_lines->{$layer_id} }, @{ $lines->{$layer_id} };
+                    }
+                }
+                return $result_lines;
+            },
+            collect_cb => sub {
+                $apply_lines->($_[0]);
+            },
+            no_threads_cb => sub {
+                for (0..$#{$self->mesh->facets}) {
+                    my $lines = $self->mesh->slice_facet($self, $_);
+                    $apply_lines->($lines);
+                }
+            },
+        );
+    }
+    die "Invalid input file\n" if !@{$self->layers};
+    
+    # remove last layer if empty
+    # (we might have created it because of the $max_layer = ... + 1 code below)
+    pop @{$self->layers} if !@{$self->layers->[-1]->surfaces} && !@{$self->layers->[-1]->lines};
+    
+    foreach my $layer (@{ $self->layers }) {
+        Slic3r::debugf "Making surfaces for layer %d (slice z = %f):\n",
+            $layer->id, unscale $layer->slice_z if $Slic3r::debug;
+        
+        # layer currently has many lines representing intersections of
+        # model facets with the layer plane. there may also be lines
+        # that we need to ignore (for example, when two non-horizontal
+        # facets share a common edge on our plane, we get a single line;
+        # however that line has no meaning for our layer as it's enclosed
+        # inside a closed polyline)
+        
+        # build surfaces from sparse lines
+        $layer->make_surfaces($self->mesh->make_loops($layer));
+        
+        # free memory
+        $layer->lines(undef);
+    }
+    
+    # detect slicing errors
+    my $warning_thrown = 0;
+    for my $i (0 .. $#{$self->layers}) {
+        my $layer = $self->layers->[$i];
+        next unless $layer->slicing_errors;
+        if (!$warning_thrown) {
+            warn "The model has overlapping or self-intersecting facets. I tried to repair it, "
+                . "however you might want to check the results or repair the input file and retry.\n";
+            $warning_thrown = 1;
+        }
+        
+        # try to repair the layer surfaces by merging all contours and all holes from
+        # neighbor layers
+        Slic3r::debugf "Attempting to repair layer %d\n", $i;
+        
+        my (@upper_surfaces, @lower_surfaces);
+        for (my $j = $i+1; $j <= $#{$self->layers}; $j++) {
+            if (!$self->layers->[$j]->slicing_errors) {
+                @upper_surfaces = @{$self->layers->[$j]->slices};
+                last;
+            }
+        }
+        for (my $j = $i-1; $j >= 0; $j--) {
+            if (!$self->layers->[$j]->slicing_errors) {
+                @lower_surfaces = @{$self->layers->[$j]->slices};
+                last;
+            }
+        }
+        
+        my $union = union_ex([
+            map $_->expolygon->contour, @upper_surfaces, @lower_surfaces,
+        ]);
+        my $diff = diff_ex(
+            [ map @$_, @$union ],
+            [ map $_->expolygon->holes, @upper_surfaces, @lower_surfaces, ],
+        );
+        
+        @{$layer->slices} = map Slic3r::Surface->new
+            (expolygon => $_, surface_type => 'internal'),
+            @$diff;
+    }
+    
+    # remove empty layers from bottom
+    while (@{$self->layers} && !@{$self->layers->[0]->slices} && !@{$self->layers->[0]->thin_walls}) {
+        shift @{$self->layers};
+        for (my $i = 0; $i <= $#{$self->layers}; $i++) {
+            $self->layers->[$i]->id($i);
+        }
+    }
+    
+    warn "No layers were detected. You might want to repair your STL file and retry.\n"
+        if !@{$self->layers};
+}
+
 sub detect_surfaces_type {
     my $self = shift;
     Slic3r::debugf "Detecting solid surfaces...\n";
diff --git a/lib/Slic3r/Skein.pm b/lib/Slic3r/Skein.pm
deleted file mode 100644
index fbcf5c2a7..000000000
--- a/lib/Slic3r/Skein.pm
+++ /dev/null
@@ -1,236 +0,0 @@
-package Slic3r::Skein;
-use Moo;
-
-use Config;
-use File::Basename qw(basename fileparse);
-use Slic3r::Geometry qw(PI unscale);
-use Time::HiRes qw(gettimeofday tv_interval);
-
-# full path (relative or absolute) to the input file
-has 'input_file'    => (is => 'ro', required => 1);
-has 'additional_input_files' => (is => 'ro', required => 0, default => sub {[]});
-
-# full path (relative or absolute) to the output file; it may contain
-# formatting variables like [layer_height] etc.
-has 'output_file'   => (is => 'rw', required => 0);
-
-has 'status_cb'     => (is => 'rw', required => 0, default => sub { sub {} });
-has 'processing_time' => (is => 'rw', required => 0);
-
-sub slice_input {
-    my $self = shift;
-    
-    my $print = Slic3r::Print->new;
-    foreach my $input_file ($self->input_file, @{$self->additional_input_files}) {
-        if ($input_file =~ /\.stl$/i) {
-            my $mesh = Slic3r::Format::STL->read_file($input_file);
-            $mesh->check_manifoldness;
-            $print->add_object_from_mesh($mesh);
-        } elsif ( $input_file =~ /\.amf(\.xml)?$/i) {
-            my ($materials, $meshes_by_material) = Slic3r::Format::AMF->read_file($input_file);
-            $_->check_manifoldness for values %$meshes_by_material;
-            $print->add_object_from_mesh($meshes_by_material->{_} || +(values %$meshes_by_material)[0]);
-        } else {
-            die "Input file must have .stl or .amf(.xml) extension\n";
-        }
-    }
-    return $print;
-}
-
-sub go {
-    my $self = shift;
-    my $t0 = [gettimeofday];
-    
-    # skein the STL into layers
-    # each layer has surfaces with holes
-    $self->status_cb->(5, "Processing input file " . $self->input_file);    
-    $self->status_cb->(10, "Processing triangulated mesh");
-    my $print = $self->slice_input;
-    $print->arrange_objects;
-    
-    # make perimeters
-    # this will add a set of extrusion loops to each layer
-    # as well as generate infill boundaries
-    $self->status_cb->(20, "Generating perimeters");
-    $_->make_perimeters for map @{$_->layers}, @{$print->objects};
-    
-    # this will clip $layer->surfaces to the infill boundaries 
-    # and split them in top/bottom/internal surfaces;
-    $self->status_cb->(30, "Detecting solid surfaces");
-    $_->detect_surfaces_type for @{$print->objects};
-    
-    # decide what surfaces are to be filled
-    $self->status_cb->(35, "Preparing infill surfaces");
-    $_->prepare_fill_surfaces for map @{$_->layers}, @{$print->objects};
-    
-    # this will remove unprintable surfaces
-    # (those that are too tight for extrusion)
-    $self->status_cb->(40, "Cleaning up");
-    $_->remove_small_surfaces for map @{$_->layers}, @{$print->objects};
-    
-    # this will detect bridges and reverse bridges
-    # and rearrange top/bottom/internal surfaces
-    $self->status_cb->(45, "Detect bridges");
-    $_->process_bridges for map @{$_->layers}, @{$print->objects};
-    
-    # this will remove unprintable perimeter loops
-    # (those that are too tight for extrusion)
-    $self->status_cb->(50, "Cleaning up the perimeters");
-    $_->remove_small_perimeters for map @{$_->layers}, @{$print->objects};
-    
-    # detect which fill surfaces are near external layers
-    # they will be split in internal and internal-solid surfaces
-    $self->status_cb->(60, "Generating horizontal shells");
-    $_->discover_horizontal_shells for @{$print->objects};
-    
-    # free memory
-    @{$_->surfaces} = () for map @{$_->layers}, @{$print->objects};
-    
-    # combine fill surfaces to honor the "infill every N layers" option
-    $self->status_cb->(70, "Combining infill");
-    $_->infill_every_layers for @{$print->objects};
-    
-    # this will generate extrusion paths for each layer
-    $self->status_cb->(80, "Infilling layers");
-    {
-        my $fill_maker = Slic3r::Fill->new('print' => $print);
-        
-        my @items = ();  # [obj_idx, layer_id]
-        foreach my $obj_idx (0 .. $#{$print->objects}) {
-            push @items, map [$obj_idx, $_], 0..$#{$print->objects->[$obj_idx]->layers};
-        }
-        Slic3r::parallelize(
-            items => [@items],
-            thread_cb => sub {
-                my $q = shift;
-                $Slic3r::Geometry::Clipper::clipper = Math::Clipper->new;
-                my $fills = {};
-                while (defined (my $obj_layer = $q->dequeue)) {
-                    my ($obj_idx, $layer_id) = @$obj_layer;
-                    $fills->{$obj_idx} ||= {};
-                    $fills->{$obj_idx}{$layer_id} = [ $fill_maker->make_fill($print->objects->[$obj_idx]->layers->[$layer_id]) ];
-                }
-                return $fills;
-            },
-            collect_cb => sub {
-                my $fills = shift;
-                foreach my $obj_idx (keys %$fills) {
-                    foreach my $layer_id (keys %{$fills->{$obj_idx}}) {
-                        @{$print->objects->[$obj_idx]->layers->[$layer_id]->fills} = @{$fills->{$obj_idx}{$layer_id}};
-                    }
-                }
-            },
-            no_threads_cb => sub {
-                foreach my $layer (map @{$_->layers}, @{$print->objects}) {
-                    @{$layer->fills} = $fill_maker->make_fill($layer);
-                }
-            },
-        );
-    }
-    
-    # generate support material
-    if ($Slic3r::support_material) {
-        $self->status_cb->(85, "Generating support material");
-        $_->generate_support_material for @{$print->objects};
-    }
-    
-    # free memory (note that support material needs fill_surfaces)
-    @{$_->fill_surfaces} = () for map @{$_->layers}, @{$print->objects};
-    
-    # make skirt
-    $self->status_cb->(88, "Generating skirt");
-    $print->make_skirt;
-    
-    # output everything to a G-code file
-    my $output_file = $self->expanded_output_filepath;
-    $self->status_cb->(90, "Exporting G-code to $output_file");
-    $print->export_gcode($output_file);
-    
-    # run post-processing scripts
-    if (@$Slic3r::post_process) {
-        $self->status_cb->(95, "Running post-processing scripts");
-        for (@$Slic3r::post_process) {
-            Slic3r::debugf "  '%s' '%s'\n", $_, $output_file;
-            system($_, $output_file);
-        }
-    }
-    
-    # output some statistics
-    $self->processing_time(tv_interval($t0));
-    printf "Done. Process took %d minutes and %.3f seconds\n", 
-        int($self->processing_time/60),
-        $self->processing_time - int($self->processing_time/60)*60;
-    
-    # TODO: more statistics!
-    printf "Filament required: %.1fmm (%.1fcm3)\n",
-        $print->total_extrusion_length, $print->total_extrusion_volume;
-}
-
-sub export_svg {
-    my $self = shift;
-    
-    my $print = $self->slice_input;
-    my $output_file = $self->expanded_output_filepath;
-    $output_file =~ s/\.gcode$/.svg/i;
-    
-    open my $fh, ">", $output_file or die "Failed to open $output_file for writing\n";
-    print "Exporting to $output_file...";
-    print $fh sprintf <<"EOF", unscale($print->total_x_length), unscale($print->total_y_length);
-<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
-<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.0//EN" "http://www.w3.org/TR/2001/REC-SVG-20010904/DTD/svg10.dtd">
-<svg width="%s" height="%s" xmlns="http://www.w3.org/2000/svg" xmlns:svg="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:slic3r="http://slic3r.org/namespaces/slic3r">
-  <!-- 
-  Generated using Slic3r $Slic3r::VERSION
-  http://slic3r.org/
-   -->
-EOF
-    
-    my $print_polygon = sub {
-        my ($polygon, $type) = @_;
-        printf $fh qq{    <polygon slic3r:type="%s" points="%s" style="fill: %s" />\n},
-            $type, (join ' ', map { join ',', map unscale $_, @$_ } @$polygon),
-            ($type eq 'contour' ? 'black' : 'white');
-    };
-    
-    foreach my $layer (@{$print->layers}) {
-        printf $fh qq{  <g id="layer%d" slic3r:z="%s">\n}, $layer->id, unscale $layer->slice_z;
-        # sort slices so that the outermost ones come first
-        my @slices = sort { $a->expolygon->contour->encloses_point($b->expolygon->contour->[0]) ? 0 : 1 } @{$layer->slices};
-        
-        foreach my $copy (@{$print->copies}) {
-            foreach my $slice (@slices) {
-                my $expolygon = $slice->expolygon->clone;
-                $expolygon->translate(@$copy);
-                $print_polygon->($expolygon->contour, 'contour');
-                $print_polygon->($_, 'hole') for $expolygon->holes;
-            }
-        }
-        print $fh qq{  </g>\n};
-    }
-    
-    print $fh "</svg>\n";
-    close $fh;
-    print "Done.\n";
-}
-
-# this method will return the value of $self->output_file after expanding its
-# format variables with their values
-sub expanded_output_filepath {
-    my $self = shift;
-    
-    my $path = $self->output_file;
-    
-    # if no explicit output file was defined, we take the input
-    # file directory and append the specified filename format
-    $path ||= (fileparse($self->input_file))[1] . $Slic3r::output_filename_format;
-    
-    my $input_filename = my $input_filename_base = basename($self->input_file);
-    $input_filename_base =~ s/\.(?:stl|amf(?:\.xml)?)$//i;
-    
-    return Slic3r::Config->replace_options($path, {
-        input_filename      => $input_filename,
-        input_filename_base => $input_filename_base,
-    });
-}
-
-1;
diff --git a/lib/Slic3r/TriangleMesh.pm b/lib/Slic3r/TriangleMesh.pm
index 63917c770..142ff5c1c 100644
--- a/lib/Slic3r/TriangleMesh.pm
+++ b/lib/Slic3r/TriangleMesh.pm
@@ -4,7 +4,7 @@ use Moo;
 use Slic3r::Geometry qw(X Y Z A B unscale same_point);
 
 # public
-has 'vertices'      => (is => 'ro', required => 1);         # id => [ [$x1,$y1],[$x2,$y2],[$x3,$y3] ]
+has 'vertices'      => (is => 'ro', required => 1);         # id => [$x,$y,$z]
 has 'facets'        => (is => 'ro', required => 1);         # id => [ $normal, $v1_id, $v2_id, $v3_id ]
 
 # private
diff --git a/slic3r.pl b/slic3r.pl
index dce403ac9..68ed125c5 100755
--- a/slic3r.pl
+++ b/slic3r.pl
@@ -74,9 +74,13 @@ if (!@ARGV && !$opt{save} && eval "require Slic3r::GUI; 1") {
 
 if (@ARGV) {
     while (my $input_file = shift @ARGV) {
-        my $skein = Slic3r::Skein->new(
-            input_file  => $input_file,
-            additional_input_files => $opt{merge} ? [ splice @ARGV, 0 ] : [],
+        my $print = Slic3r::Print->new;
+        $print->add_object_from_file($input_file);
+        if ($opt{merge}) {
+            $print->add_object_from_file($_) for splice @ARGV, 0;
+        }
+        $print->duplicate;
+        my %params = (
             output_file => $opt{output},
             status_cb   => sub {
                 my ($percent, $message) = @_;
@@ -84,9 +88,9 @@ if (@ARGV) {
             },
         );
         if ($opt{export_svg}) {
-            $skein->export_svg;
+            $print->export_svg(%params);
         } else {
-            $skein->go;
+            $print->export_gcode(%params);
         }
     }
 } else {
@@ -125,7 +129,7 @@ $j
     --post-process      Generated G-code will be processed with the supplied script;
                         call this more than once to process through multiple scripts.
     --export-svg        Export a SVG file containing slices instead of G-code.
-    --merge             If multiple files are supplied, they will be composed into a single 
+    -m, --merge         If multiple files are supplied, they will be composed into a single 
                         print rather than processed individually.
   
   Printer options: