diff --git a/lib/Slic3r.pm b/lib/Slic3r.pm
index 65d83f96e..911df206d 100644
--- a/lib/Slic3r.pm
+++ b/lib/Slic3r.pm
@@ -52,6 +52,7 @@ use Slic3r::GCode::ArcFitting;
 use Slic3r::GCode::CoolingBuffer;
 use Slic3r::GCode::Layer;
 use Slic3r::GCode::MotionPlanner;
+use Slic3r::GCode::OozePrevention;
 use Slic3r::GCode::PlaceholderParser;
 use Slic3r::GCode::Reader;
 use Slic3r::GCode::SpiralVase;
diff --git a/lib/Slic3r/Config.pm b/lib/Slic3r/Config.pm
index fab693b12..d1aeb38cf 100644
--- a/lib/Slic3r/Config.pm
+++ b/lib/Slic3r/Config.pm
@@ -432,6 +432,9 @@ sub read_ini {
     return $ini;
 }
 
+package Slic3r::Config::GCode;
+use parent 'Slic3r::Config';
+
 package Slic3r::Config::Print;
 use parent 'Slic3r::Config';
 
diff --git a/lib/Slic3r/Extruder.pm b/lib/Slic3r/Extruder.pm
index 51e7ad2a6..404dc14bc 100644
--- a/lib/Slic3r/Extruder.pm
+++ b/lib/Slic3r/Extruder.pm
@@ -29,16 +29,6 @@ sub retract_speed_mm_min {
     return $self->retract_speed * 60;
 }
 
-sub scaled_wipe_distance {
-    my ($self, $travel_speed) = @_;
-    
-    # how far do we move in XY at travel_speed for the time needed to consume
-    # retract_length at retract_speed?
-    # reduce feedrate a bit; travel speed is often too high to move on existing material
-    # too fast = ripping of existing material; too slow = short wipe path, thus more blob
-    return scale($self->retract_length / $self->retract_speed * $travel_speed * 0.8);
-}
-
 sub extruded_volume {
     my ($self, $E) = @_;
     return $E * ($self->filament_diameter**2) * PI/4;
diff --git a/lib/Slic3r/GCode.pm b/lib/Slic3r/GCode.pm
index e5d60c383..9b8ed1622 100644
--- a/lib/Slic3r/GCode.pm
+++ b/lib/Slic3r/GCode.pm
@@ -9,12 +9,14 @@ use Slic3r::Geometry qw(epsilon scale unscale scaled_epsilon points_coincide PI
 use Slic3r::Geometry::Clipper qw(union_ex offset_ex);
 use Slic3r::Surface ':types';
 
+extends 'Slic3r::GCode::Base';
+
 has 'config'             => (is => 'ro', default => sub { Slic3r::Config::Full->new });
 has 'placeholder_parser' => (is => 'rw', default => sub { Slic3r::GCode::PlaceholderParser->new });
-has 'standby_points'     => (is => 'rw');
+has 'ooze_prevention'    => (is => 'rw');
 has 'enable_loop_clipping' => (is => 'rw', default => sub {1});
 has 'enable_wipe'        => (is => 'rw', default => sub {0});   # at least one extruder has wipe enabled
-has 'layer_count'        => (is => 'ro', required => 1 );
+has 'layer_count'        => (is => 'ro');
 has '_layer_index'       => (is => 'rw', default => sub {-1});  # just a counter
 has 'layer'              => (is => 'rw');
 has '_layer_islands'     => (is => 'rw');
@@ -23,32 +25,28 @@ has '_seam_position'     => (is => 'ro', default => sub { {} });  # $object => p
 has 'shift_x'            => (is => 'rw', default => sub {0} );
 has 'shift_y'            => (is => 'rw', default => sub {0} );
 has 'z'                  => (is => 'rw');
-has 'extruders'          => (is => 'ro', default => sub {{}});
-has 'multiple_extruders' => (is => 'rw', default => sub {0});
-has 'extruder'           => (is => 'rw');
 has 'external_mp'        => (is => 'rw');
 has 'layer_mp'           => (is => 'rw');
 has 'new_object'         => (is => 'rw', default => sub {0});
 has 'straight_once'      => (is => 'rw', default => sub {1});
 has 'elapsed_time'       => (is => 'rw', default => sub {0} );  # seconds
-has 'lifted'             => (is => 'rw', default => sub {0} );
 has 'last_pos'           => (is => 'rw', default => sub { Slic3r::Point->new(0,0) } );
-has 'last_fan_speed'     => (is => 'rw', default => sub {0});
-has 'last_acceleration'  => (is => 'rw', default => sub {0});
 has 'wipe_path'          => (is => 'rw');
 
+sub apply_print_config {
+    my ($self, $print_config) = @_;
+    
+    $self->SUPER::apply_print_config($print_config);
+    $self->config->apply_print_config($print_config);
+}
+
 sub set_extruders {
-    my ($self, $extruder_ids, $print_config) = @_;
+    my ($self, $extruder_ids) = @_;
     
-    foreach my $i (@$extruder_ids) {
-        $self->extruders->{$i} = my $e = Slic3r::Extruder->new($i, $print_config);
-        $self->enable_wipe(1) if $e->wipe;
-    }
+    $self->SUPER::set_extruders($extruder_ids);
     
-    # we enable support for multiple extruder if any extruder greater than 0 is used
-    # (even if prints only uses that one) since we need to output Tx commands
-    # first extruder has index 0
-    $self->multiple_extruders(max(@$extruder_ids) > 0);
+    # enable wipe path generation if any extruder has wipe enabled
+    $self->enable_wipe(defined first { $_->wipe } values %{$self->_extruders});
 }
 
 sub set_shift {
@@ -82,49 +80,17 @@ sub change_layer {
     }
     
     my $gcode = "";
-    if ($self->config->gcode_flavor =~ /^(?:makerware|sailfish)$/) {
+    if (defined $self->layer_count) {
         # TODO: cap this to 99% and add an explicit M73 P100 in the end G-code
-        $gcode .= sprintf "M73 P%s%s\n",
-            int(99 * ($self->_layer_index / ($self->layer_count - 1))),
-            ($self->config->gcode_comments ? ' ; update progress' : '');
+        $gcode .= $self->update_progress(int(99 * ($self->_layer_index / ($self->layer_count - 1))));
     }
     
-    $gcode .= $self->move_z($layer->print_z);
-    return $gcode;
-}
-
-# this method accepts Z in unscaled coordinates
-sub move_z {
-    my ($self, $z, $comment) = @_;
-    
-    my $gcode = "";
-    
-    $z += $self->config->z_offset;
-    my $current_z = $self->z;
-    my $nominal_z = defined $current_z ? ($current_z - $self->lifted) : undef;
-    
-    if (!defined $current_z || $z > $current_z || $z < $nominal_z) {
-        # we're moving above the current actual Z (so above the lift height of the current
-        # layer if any) or below the current nominal layer
-        
-        # in both cases, we're going to the nominal Z of the next layer
-        $self->lifted(0);
-        
-        if ($self->extruder->retract_layer_change) {
-            # this retraction may alter $self->z
-            $gcode .= $self->retract(move_z => $z);
-            $current_z = $self->z;  # update current z in case retract() changed it
-            $nominal_z = defined $current_z ? ($current_z - $self->lifted) : undef;
-        }
-        $gcode .= $self->G0(undef, $z, 0, $self->config->travel_speed*60, $comment || ('move to next layer (' . $self->layer->id . ')'))
-            if !defined $current_z || abs($z - $nominal_z) > epsilon;
-    } elsif ($z < $current_z) {
-        # we're moving above the current nominal layer height and below the current actual one.
-        # we're basically advancing to next layer, whose nominal Z is still lower than the previous
-        # layer Z with lift.
-        $self->lifted($current_z - $z);
+    my $z = $layer->print_z + $self->config->z_offset;  # in unscaled coordinates
+    if ($self->_extruder->retract_layer_change && $self->will_move_z($z)) {
+        $gcode .= $self->retract;
+        $gcode .= $self->lift;
     }
-    
+    $gcode .= $self->travel_to_z($z, 'move to next layer (' . $self->layer->id . ')');
     return $gcode;
 }
 
@@ -154,7 +120,7 @@ sub extrude_loop {
     } elsif ($self->config->seam_position eq 'nearest' || $self->config->seam_position eq 'aligned') {
         # simplify polygon in order to skip false positives in concave/convex detection
         my $polygon = $loop->polygon;
-        my @simplified = @{$polygon->simplify(scale $self->extruder->nozzle_diameter/2)};
+        my @simplified = @{$polygon->simplify(scale $self->_extruder->nozzle_diameter/2)};
         
         # concave vertices have priority
         my @candidates = map @{$_->concave_points(PI*4/3)}, @simplified;
@@ -200,7 +166,7 @@ sub extrude_loop {
     # if polyline was shorter than the clipping distance we'd get a null polyline, so
     # we discard it in that case
     my $clip_length = $self->enable_loop_clipping
-        ? scale($self->extruder->nozzle_diameter) * &Slic3r::LOOP_CLIPPING_LENGTH_OVER_NOZZLE_DIAMETER
+        ? scale($self->_extruder->nozzle_diameter) * &Slic3r::LOOP_CLIPPING_LENGTH_OVER_NOZZLE_DIAMETER
         : 0;
     
     # get paths
@@ -234,7 +200,7 @@ sub extrude_loop {
         # we make sure we don't exceed the segment length because we don't know
         # the rotation of the second segment so we might cross the object boundary
         my $first_segment = Slic3r::Line->new(@$last_path_polyline[0,1]);
-        my $distance = min(scale($self->extruder->nozzle_diameter), $first_segment->length);
+        my $distance = min(scale($self->_extruder->nozzle_diameter), $first_segment->length);
         my $point = $first_segment->point_at($distance);
         $point->rotate($angle, $last_path_polyline->first_point);
         
@@ -290,8 +256,8 @@ sub _extrude_path {
     }
     
     # calculate extrusion length per distance unit
-    my $e = $self->extruder->e_per_mm3 * $path->mm3_per_mm;
-    $e = 0 if !$self->config->get_extrusion_axis;
+    my $e_per_mm = $self->_extruder->e_per_mm3 * $path->mm3_per_mm;
+    $e_per_mm = 0 if !$self->_extrusion_axis;
     
     # set speed
     my $F;
@@ -323,10 +289,10 @@ sub _extrude_path {
     $gcode .= ";_BRIDGE_FAN_START\n" if $path->is_bridge;
     my $path_length = unscale $path->length;
     {
-        $gcode .= $path->gcode($self->extruder, $e, $F,
-            $self->shift_x - $self->extruder->extruder_offset->x,
-            $self->shift_y - $self->extruder->extruder_offset->y,  #,,
-            $self->config->get_extrusion_axis,
+        $gcode .= $path->gcode($self->_extruder, $e_per_mm, $F,
+            $self->shift_x - $self->_extruder->extruder_offset->x,
+            $self->shift_y - $self->_extruder->extruder_offset->y,  #,,
+            $self->_extrusion_axis,
             $self->config->gcode_comments ? " ; $description" : "");
 
         if ($self->enable_wipe) {
@@ -358,7 +324,7 @@ sub travel_to {
     
     # skip retraction if the travel move is contained in an island in the current layer
     # *and* in an island in the upper layer (so that the ooze will not be visible)
-    if ($travel->length < scale $self->extruder->retract_before_travel
+    if ($travel->length < scale $self->_extruder->retract_before_travel
         || ($self->config->only_retract_when_crossing_perimeters
             && $self->config->fill_density > 0
             && (first { $_->contains_line($travel) } @{$self->_upper_layer_islands})
@@ -366,11 +332,11 @@ sub travel_to {
         || (defined $role && $role == EXTR_ROLE_SUPPORTMATERIAL && (first { $_->contains_line($travel) } @{$self->layer->support_islands}))
         ) {
         $self->straight_once(0);
-        $gcode .= $self->G0($point, undef, 0, $self->config->travel_speed*60, $comment || "");
+        $gcode .= $self->travel_to_xy($self->point_to_gcode($point), $comment);
     } elsif (!$self->config->avoid_crossing_perimeters || $self->straight_once) {
         $self->straight_once(0);
         $gcode .= $self->retract;
-        $gcode .= $self->G0($point, undef, 0, $self->config->travel_speed*60, $comment || "");
+        $gcode .= $self->travel_to_xy($self->point_to_gcode($point), $comment);
     } else {
         if ($self->new_object) {
             $self->new_object(0);
@@ -411,83 +377,75 @@ sub _plan {
         }
     }
     
-    # do the retract (the travel_to argument is broken)
+    # perform the retraction
     $gcode .= $self->retract if $need_retract;
     
     # append the actual path and return
     # use G1 because we rely on paths being straight (G0 may make round paths)
-    $gcode .= join '', map $self->G1($_->b, undef, 0, $self->config->travel_speed*60, $comment || ""), @travel;
+    $gcode .= join '',
+        map $self->travel_to_xy($self->point_to_gcode($_->b), $comment),
+        @travel;
     return $gcode;
 }
 
 sub retract {
-    my ($self, %params) = @_;
+    my ($self, $toolchange) = @_;
     
-    # get the retraction length and abort if none
-    my ($length, $restart_extra, $comment) = $params{toolchange}
-        ? ($self->extruder->retract_length_toolchange,  $self->extruder->retract_restart_extra_toolchange,  "retract for tool change")
-        : ($self->extruder->retract_length,             $self->extruder->retract_restart_extra,             "retract");
+    return "" if !defined $self->_extruder;
     
-    # if we already retracted, reduce the required amount of retraction
-    $length -= $self->extruder->retracted;
-    return "" unless $length > 0;
     my $gcode = "";
     
-    # wipe
-    my $wipe_path;
-    if ($self->extruder->wipe && $self->wipe_path) {
-        my @points = @{$self->wipe_path};
-        $wipe_path = Slic3r::Polyline->new($self->last_pos, @{$self->wipe_path}[1..$#{$self->wipe_path}]);
-        $wipe_path->clip_end($wipe_path->length - $self->extruder->scaled_wipe_distance($self->config->travel_speed));
-    }
-    
-    # prepare moves
-    my $retract = [undef, undef, -$length, $self->extruder->retract_speed_mm_min, $comment];
-    my $lift    = ($self->config->retract_lift->[0] == 0 || defined $params{move_z}) && !$self->lifted
-        ? undef
-        : [undef, $self->z + $self->config->retract_lift->[0], 0, $self->config->travel_speed*60, 'lift plate during travel'];
-    
-    # check that we have a positive wipe length
-    if ($wipe_path) {
-        # subdivide the retraction
+    # wipe (if it's enabled for this extruder and we have a stored wipe path)
+    if ($self->_extruder->wipe && $self->wipe_path) {
+        # Reduce feedrate a bit; travel speed is often too high to move on existing material.
+        # Too fast = ripping of existing material; too slow = short wipe path, thus more blob.
+        my $wipe_speed = $self->gcode_config->travel_speed * 0.8;
+        
+        # get the retraction length
+        my $length = $toolchange
+            ? $self->_extruder->retract_length
+            : $self->_extruder->retract_length_toolchange;
+        
+        # Calculate how long we need to travel in order to consume the required
+        # amount of retraction. In other words, how far do we move in XY at $wipe_speed
+        # for the time needed to consume retract_length at retract_speed?
+        my $wipe_dist = scale($length / $self->_extruder->retract_speed * $wipe_speed);
+        
+        # Take the stored wipe path and replace first point with the current actual position
+        # (they might be different, for example, in case of loop clipping).
+        my $wipe_path = Slic3r::Polyline->new(
+            $self->last_pos,
+            @{$self->wipe_path}[1..$#{$self->wipe_path}],
+        );
+        # 
+        $wipe_path->clip_end($wipe_path->length - $wipe_dist);
+        
+        # subdivide the retraction in segments
         my $retracted = 0;
         foreach my $line (@{$wipe_path->lines}) {
             my $segment_length = $line->length;
-            # reduce retraction length a bit to avoid effective retraction speed to be greater than the configured one
-            # due to rounding
-            my $e = $retract->[2] * ($segment_length / $self->extruder->scaled_wipe_distance($self->config->travel_speed)) * 0.95;
-            $retracted += $e;
-            $gcode .= $self->G1($line->b, undef, $e, $self->config->travel_speed*60*0.8, $retract->[3] . ";_WIPE");
+            # Reduce retraction length a bit to avoid effective retraction speed to be greater than the configured one
+            # due to rounding (TODO: test and/or better math for this)
+            my $dE = $length * ($segment_length / $wipe_dist) * 0.95;
+            $gcode .= $self->set_speed($wipe_speed*60);
+            $gcode .= $self->extrude_to_xy(
+                $self->point_to_gcode($line->b),
+                -$dE,
+                'retract;_WIPE',
+            );
+            $retracted += $dE;
         }
-        if ($retracted > $retract->[2]) {
-            # if we retracted less than we had to, retract the remainder
-            # TODO: add regression test
-            $gcode .= $self->G1(undef, undef, $retract->[2] - $retracted, $self->extruder->retract_speed_mm_min, $comment);
-        }
-        $gcode .= $self->reset_e;
-    } elsif ($self->config->use_firmware_retraction) {
-        $gcode .= "G10 ; retract\n";
-    } else {
-        $gcode .= $self->G1(@$retract);
-    
-        # reset extrusion distance during retracts
-        # this makes sure we leave sufficient precision in the firmware
-        $gcode .= $self->reset_e;
+        $self->_extruder->set_retracted($self->_extruder->retracted + $retracted);
     }
-    if (!$self->lifted) {
-        if (defined $params{move_z} && $self->config->retract_lift->[0] > 0) {
-            my $travel = [undef, $params{move_z} + $self->config->retract_lift->[0], 0, $self->config->travel_speed*60, 'move to next layer (' . $self->layer->id . ') and lift'];
-            $gcode .= $self->G0(@$travel);
-            $self->lifted($self->config->retract_lift->[0]);
-        } elsif ($lift) {
-            $gcode .= $self->G1(@$lift);
-        }
-    }
-    $self->extruder->set_retracted($self->extruder->retracted + $length);
-    $self->extruder->set_restart_extra($restart_extra);
-    $self->lifted($self->config->retract_lift->[0]) if $lift;
     
-    $gcode .= "M103 ; extruder off\n" if $self->config->gcode_flavor eq 'makerware';
+    # The parent class will decide whether we need to perform an actual retraction
+    # (the extruder might be already retracted fully or partially). We call these 
+    # methods even if we performed wipe, since this will ensure the entire retraction
+    # length is honored in case wipe path was too short.p
+    $gcode .= $toolchange ? $self->retract_for_toolchange : $self->SUPER::retract;
+    
+    $gcode .= $self->reset_e;
+    $gcode .= $self->lift;
     
     return $gcode;
 }
@@ -496,53 +454,11 @@ sub unretract {
     my ($self) = @_;
     
     my $gcode = "";
-    $gcode .= "M101 ; extruder on\n" if $self->config->gcode_flavor eq 'makerware';
-    
-    if ($self->lifted) {
-        $gcode .= $self->G0(undef, $self->z - $self->lifted, 0, $self->config->travel_speed*60, 'restore layer Z');
-        $self->lifted(0);
-    }
-    
-    my $to_unretract = $self->extruder->retracted + $self->extruder->restart_extra;
-    if ($to_unretract) {
-        if ($self->config->use_firmware_retraction) {
-            $gcode .= "G11 ; unretract\n";
-            $gcode .= $self->reset_e;
-        } elsif ($self->config->get_extrusion_axis) {
-            # use G1 instead of G0 because G0 will blend the restart with the previous travel move
-            $gcode .= sprintf "G1 %s%.5f F%.3f",
-                $self->config->get_extrusion_axis,
-                $self->extruder->extrude($to_unretract),
-                $self->extruder->retract_speed_mm_min;
-            $gcode .= " ; compensate retraction" if $self->config->gcode_comments;
-            $gcode .= "\n";
-        }
-        $self->extruder->set_retracted(0);
-        $self->extruder->set_restart_extra(0);
-    }
-    
+    $gcode .= $self->unlift;
+    $gcode .= $self->SUPER::unretract('compensate retraction');
     return $gcode;
 }
 
-sub reset_e {
-    my ($self) = @_;
-    return "" if $self->config->gcode_flavor =~ /^(?:mach3|makerware|sailfish)$/;
-    
-    $self->extruder->set_E(0) if $self->extruder;
-    return sprintf "G92 %s0%s\n", $self->config->get_extrusion_axis, ($self->config->gcode_comments ? ' ; reset extrusion distance' : '')
-        if $self->config->get_extrusion_axis && !$self->config->use_relative_e_distances;
-}
-
-sub set_acceleration {
-    my ($self, $acceleration) = @_;
-    
-    return "" if !$acceleration || $acceleration == $self->last_acceleration;
-    
-    $self->last_acceleration($acceleration);
-    return sprintf "M204 S%s%s\n",
-        $acceleration, ($self->config->gcode_comments ? ' ; adjust acceleration' : '');
-}
-
 sub G0 {
     my $self = shift;
     return $self->G1(@_) if !($self->config->g0 || $self->config->gcode_flavor eq 'mach3');
@@ -559,8 +475,8 @@ sub _G0_G1 {
     
     if ($point) {
         $gcode .= sprintf " X%.3f Y%.3f", 
-            ($point->x * &Slic3r::SCALING_FACTOR) + $self->shift_x - $self->extruder->extruder_offset->x,
-            ($point->y * &Slic3r::SCALING_FACTOR) + $self->shift_y - $self->extruder->extruder_offset->y; #**
+            ($point->x * &Slic3r::SCALING_FACTOR) + $self->shift_x - $self->_extruder->extruder_offset->x,
+            ($point->y * &Slic3r::SCALING_FACTOR) + $self->shift_y - $self->_extruder->extruder_offset->y; #**
         $self->last_pos($point->clone);
     }
     if (defined $z && (!defined $self->z || $z != $self->z)) {
@@ -571,14 +487,24 @@ sub _G0_G1 {
     return $self->_Gx($gcode, $e, $F, $comment);
 }
 
+# convert a model-space scaled point into G-code coordinates
+sub point_to_gcode {
+    my ($self, $point) = @_;
+    
+    return Slic3r::Pointf->new(
+        ($point->x * &Slic3r::SCALING_FACTOR) + $self->shift_x - $self->_extruder->extruder_offset->x,
+        ($point->y * &Slic3r::SCALING_FACTOR) + $self->shift_y - $self->_extruder->extruder_offset->y, #**
+    );
+}
+
 sub _Gx {
     my ($self, $gcode, $e, $F, $comment) = @_;
     
     $gcode .= sprintf " F%.3f", $F;
     
     # output extrusion distance
-    if ($e && $self->config->get_extrusion_axis) {
-        $gcode .= sprintf " %s%.5f", $self->config->get_extrusion_axis, $self->extruder->extrude($e);
+    if ($e && $self->_extrusion_axis) {
+        $gcode .= sprintf " %s%.5f", $self->_extrusion_axis, $self->_extruder->extrude($e);
     }
     
     $gcode .= " ; $comment" if $comment && $self->config->gcode_comments;
@@ -588,124 +514,35 @@ sub _Gx {
 sub set_extruder {
     my ($self, $extruder_id) = @_;
     
-    # return nothing if this extruder was already selected
-    return "" if (defined $self->extruder) && ($self->extruder->id == $extruder_id);
+    return "" if !$self->need_toolchange($extruder_id);
     
     # if we are running a single-extruder setup, just set the extruder and return nothing
-    if (!$self->multiple_extruders) {
-        $self->extruder($self->extruders->{$extruder_id});
-        return "";
+    if (!$self->_multiple_extruders) {
+        return $self->_toolchange($extruder_id);
     }
     
-    # trigger retraction on the current extruder (if any) 
-    my $gcode = "";
-    $gcode .= $self->retract(toolchange => 1) if defined $self->extruder;
+    # prepend retraction on the current extruder
+    my $gcode = $self->retract(1);
     
     # append custom toolchange G-code
-    if (defined $self->extruder && $self->config->toolchange_gcode) {
+    if (defined $self->_extruder && $self->config->toolchange_gcode) {
         $gcode .= sprintf "%s\n", $self->placeholder_parser->process($self->config->toolchange_gcode, {
-            previous_extruder   => $self->extruder->id,
+            previous_extruder   => $self->_extruder->id,
             next_extruder       => $extruder_id,
         });
     }
     
-    # set the current extruder to the standby temperature
-    if ($self->standby_points && defined $self->extruder) {
-        # move to the nearest standby point
-        {
-            my $last_pos = $self->last_pos->clone;
-            $last_pos->translate(scale +$self->shift_x, scale +$self->shift_y);
-            my $standby_point = $last_pos->nearest_point($self->standby_points);
-            $standby_point->translate(scale -$self->shift_x, scale -$self->shift_y);
-            $gcode .= $self->travel_to($standby_point);
-        }
-        
-        if ($self->config->standby_temperature_delta != 0) {
-            my $temp = defined $self->layer && $self->layer->id == 0
-                ? $self->extruder->first_layer_temperature
-                : $self->extruder->temperature;
-            # we assume that heating is always slower than cooling, so no need to block
-            $gcode .= $self->set_temperature($temp + $self->config->standby_temperature_delta, 0);
-        }
-    }
+    # if ooze prevention is enabled, park current extruder in the nearest
+    # standby point and set it to the standby temperature
+    $gcode .= $self->ooze_prevention->pre_toolchange($self)
+        if $self->ooze_prevention && defined $self->_extruder;
     
-    # set the new extruder
-    $self->extruder($self->extruders->{$extruder_id});
-    $gcode .= sprintf "%s%d%s\n", 
-        ($self->config->gcode_flavor eq 'makerware'
-            ? 'M135 T'
-            : $self->config->gcode_flavor eq 'sailfish'
-                ? 'M108 T'
-                : 'T'),
-        $extruder_id,
-        ($self->config->gcode_comments ? ' ; change extruder' : '');
-    
-    $gcode .= $self->reset_e;
+    # append the toolchange command
+    $gcode .= $self->_toolchange($extruder_id);
     
     # set the new extruder to the operating temperature
-    if ($self->config->ooze_prevention && $self->config->standby_temperature_delta != 0) {
-        my $temp = defined $self->layer && $self->layer->id == 0
-            ? $self->extruder->first_layer_temperature
-            : $self->extruder->temperature;
-        $gcode .= $self->set_temperature($temp, 1);
-    }
-    
-    return $gcode;
-}
-
-sub set_fan {
-    my ($self, $speed, $dont_save) = @_;
-    
-    if ($self->last_fan_speed != $speed || $dont_save) {
-        $self->last_fan_speed($speed) if !$dont_save;
-        if ($speed == 0) {
-            my $code = $self->config->gcode_flavor eq 'teacup'
-                ? 'M106 S0'
-                : $self->config->gcode_flavor =~ /^(?:makerware|sailfish)$/
-                    ? 'M127'
-                    : 'M107';
-            return sprintf "$code%s\n", ($self->config->gcode_comments ? ' ; disable fan' : '');
-        } else {
-            if ($self->config->gcode_flavor =~ /^(?:makerware|sailfish)$/) {
-                return sprintf "M126%s\n", ($self->config->gcode_comments ? ' ; enable fan' : '');
-            } else {
-                return sprintf "M106 %s%d%s\n", ($self->config->gcode_flavor eq 'mach3' ? 'P' : 'S'),
-                    (255 * $speed / 100), ($self->config->gcode_comments ? ' ; enable fan' : '');
-            }
-        }
-    }
-    return "";
-}
-
-sub set_temperature {
-    my ($self, $temperature, $wait, $tool) = @_;
-    
-    return "" if $wait && $self->config->gcode_flavor =~ /^(?:makerware|sailfish)$/;
-    
-    my ($code, $comment) = ($wait && $self->config->gcode_flavor ne 'teacup')
-        ? ('M109', 'wait for temperature to be reached')
-        : ('M104', 'set temperature');
-    my $gcode = sprintf "$code %s%d %s; $comment\n",
-        ($self->config->gcode_flavor eq 'mach3' ? 'P' : 'S'), $temperature,
-        (defined $tool && ($self->multiple_extruders || $self->config->gcode_flavor =~ /^(?:makerware|sailfish)$/)) ? "T$tool " : "";
-    
-    $gcode .= "M116 ; wait for temperature to be reached\n"
-        if $self->config->gcode_flavor eq 'teacup' && $wait;
-    
-    return $gcode;
-}
-
-sub set_bed_temperature {
-    my ($self, $temperature, $wait) = @_;
-    
-    my ($code, $comment) = ($wait && $self->config->gcode_flavor ne 'teacup')
-        ? (($self->config->gcode_flavor =~ /^(?:makerware|sailfish)$/ ? 'M109' : 'M190'), 'wait for bed temperature to be reached')
-        : ('M140', 'set bed temperature');
-    my $gcode = sprintf "$code %s%d ; $comment\n",
-        ($self->config->gcode_flavor eq 'mach3' ? 'P' : 'S'), $temperature;
-    
-    $gcode .= "M116 ; wait for bed temperature to be reached\n"
-        if $self->config->gcode_flavor eq 'teacup' && $wait;
+    $gcode .= $self->ooze_prevention->post_toolchange($self)
+        if $self->ooze_prevention;
     
     return $gcode;
 }
diff --git a/lib/Slic3r/GCode/Base.pm b/lib/Slic3r/GCode/Base.pm
new file mode 100644
index 000000000..78a06d88f
--- /dev/null
+++ b/lib/Slic3r/GCode/Base.pm
@@ -0,0 +1,408 @@
+package Slic3r::GCode::Base;
+use Moo;
+
+use List::Util qw(min max first);
+use Slic3r::Geometry qw(X Y epsilon);
+
+has 'gcode_config'          => (is => 'ro', default => sub { Slic3r::Config::GCode->new });
+has '_extrusion_axis'       => (is => 'rw', default => sub { 'E' });
+has '_extruders'            => (is => 'ro', default => sub {{}});
+has '_extruder'             => (is => 'rw');
+has '_multiple_extruders'   => (is => 'rw', default => sub { 0 });
+has '_last_acceleration'    => (is => 'rw', default => sub { 0 });
+has '_last_fan_speed'       => (is => 'rw', default => sub { 0 });
+has '_lifted'               => (is => 'rw', default => sub { 0 });
+has '_pos'                  => (is => 'rw', default => sub { Slic3r::Pointf3->new });
+
+sub apply_print_config {
+    my ($self, $print_config) = @_;
+    
+    $self->gcode_config->apply_print_config($print_config);
+    
+    if ($self->gcode_config->gcode_flavor eq 'mach3') {
+        $self->_extrusion_axis('A');
+    } elsif ($self->gcode_config->gcode_flavor eq 'no-extrusion') {
+        $self->_extrusion_axis('');
+    } else {
+        $self->_extrusion_axis($self->gcode_config->extrusion_axis);
+    }
+}
+
+sub set_extruders {
+    my ($self, $extruder_ids) = @_;
+    
+    foreach my $i (@$extruder_ids) {
+        $self->_extruders->{$i} = my $e = Slic3r::Extruder->new($i, $self->config);
+    }
+    
+    # we enable support for multiple extruder if any extruder greater than 0 is used
+    # (even if prints only uses that one) since we need to output Tx commands
+    # first extruder has index 0
+    $self->_multiple_extruders(max(@$extruder_ids) > 0);
+}
+
+sub set_temperature {
+    my ($self, $temperature, $wait, $tool) = @_;
+    
+    return "" if $wait && $self->gcode_config->gcode_flavor =~ /^(?:makerware|sailfish)$/;
+    
+    my ($code, $comment) = ($wait && $self->gcode_config->gcode_flavor ne 'teacup')
+        ? ('M109', 'wait for temperature to be reached')
+        : ('M104', 'set temperature');
+    my $gcode = sprintf "$code %s%d %s; $comment\n",
+        ($self->gcode_config->gcode_flavor eq 'mach3' ? 'P' : 'S'), $temperature,
+        (defined $tool && ($self->_multiple_extruders || $self->gcode_config->gcode_flavor =~ /^(?:makerware|sailfish)$/)) ? "T$tool " : "";
+    
+    $gcode .= "M116 ; wait for temperature to be reached\n"
+        if $self->gcode_config->gcode_flavor eq 'teacup' && $wait;
+    
+    return $gcode;
+}
+
+sub set_bed_temperature {
+    my ($self, $temperature, $wait) = @_;
+    
+    my ($code, $comment) = ($wait && $self->gcode_config->gcode_flavor ne 'teacup')
+        ? (($self->gcode_config->gcode_flavor =~ /^(?:makerware|sailfish)$/ ? 'M109' : 'M190'), 'wait for bed temperature to be reached')
+        : ('M140', 'set bed temperature');
+    my $gcode = sprintf "$code %s%d ; $comment\n",
+        ($self->gcode_config->gcode_flavor eq 'mach3' ? 'P' : 'S'), $temperature;
+    
+    $gcode .= "M116 ; wait for bed temperature to be reached\n"
+        if $self->gcode_config->gcode_flavor eq 'teacup' && $wait;
+    
+    return $gcode;
+}
+
+sub set_fan {
+    my ($self, $speed, $dont_save) = @_;
+    
+    if ($self->_last_fan_speed != $speed || $dont_save) {
+        $self->_last_fan_speed($speed) if !$dont_save;
+        if ($speed == 0) {
+            my $code = $self->gcode_config->gcode_flavor eq 'teacup'
+                ? 'M106 S0'
+                : $self->gcode_config->gcode_flavor =~ /^(?:makerware|sailfish)$/
+                    ? 'M127'
+                    : 'M107';
+            return sprintf "$code%s\n", ($self->gcode_config->gcode_comments ? ' ; disable fan' : '');
+        } else {
+            if ($self->gcode_config->gcode_flavor =~ /^(?:makerware|sailfish)$/) {
+                return sprintf "M126%s\n", ($self->gcode_config->gcode_comments ? ' ; enable fan' : '');
+            } else {
+                return sprintf "M106 %s%d%s\n", ($self->gcode_config->gcode_flavor eq 'mach3' ? 'P' : 'S'),
+                    (255 * $speed / 100), ($self->gcode_config->gcode_comments ? ' ; enable fan' : '');
+            }
+        }
+    }
+    return "";
+}
+
+sub set_acceleration {
+    my ($self, $acceleration) = @_;
+    
+    return "" if !$acceleration || $acceleration == $self->_last_acceleration;
+    
+    $self->_last_acceleration($acceleration);
+    return sprintf "M204 S%s%s\n",
+        $acceleration, ($self->gcode_config->gcode_comments ? ' ; adjust acceleration' : '');
+}
+
+sub update_progress {
+    my ($self, $percent) = @_;
+    
+    return "" if $self->gcode_config->gcode_flavor !~ /^(?:makerware|sailfish)$/;
+    return sprintf "M73 P%s%s\n",
+        int($percent),
+        $self->_comment('update progress');
+}
+
+sub need_toolchange {
+    my ($self, $extruder_id) = @_;
+    
+    # return false if this extruder was already selected
+    return (!defined $self->_extruder) || ($self->_extruder->id != $extruder_id);
+}
+
+sub set_extruder {
+    my ($self, $extruder_id) = @_;
+    
+    return "" if !$self->need_toolchange;
+    return $self->_toolchange($extruder_id);
+}
+
+sub _toolchange {
+    my ($self, $extruder_id) = @_;
+    
+    # set the new extruder
+    $self->_extruder($self->_extruders->{$extruder_id});
+    
+    # return the toolchange command
+    # if we are running a single-extruder setup, just set the extruder and return nothing
+    my $gcode = "";
+    if ($self->_multiple_extruders) {
+        $gcode .= sprintf "%s%d%s\n",
+            ($self->gcode_config->gcode_flavor eq 'makerware'
+                ? 'M135 T'
+                : $self->gcode_config->gcode_flavor eq 'sailfish'
+                    ? 'M108 T'
+                    : 'T'),
+            $extruder_id,
+            ($self->gcode_config->gcode_comments ? ' ; change extruder' : '');
+        
+        $gcode .= $self->reset_e(1);
+    }
+    return $gcode;
+}
+
+sub reset_e {
+    my ($self, $force) = @_;
+    
+    return "" if $self->config->gcode_flavor =~ /^(?:mach3|makerware|sailfish)$/;
+    
+    if (defined $self->_extruder) {
+        return "" if $self->_extruder->E == 0 && !$force;
+        $self->_extruder->set_E(0) if $self->_extruder;
+    }
+    
+    if ($self->_extrusion_axis ne '' && !$self->gcode_config->use_relative_e_distances) {
+        return sprintf "G92 %s0%s\n", $self->gcode_config->extrusion_axis, ($self->config->gcode_comments ? ' ; reset extrusion distance' : '');
+    } else {
+        return "";
+    }
+}
+
+sub _comment {
+    my ($self, $comment) = @_;
+    
+    return "" if (!defined $comment) || ($comment eq '') || !$self->config->gcode_comments;
+    return " ; $comment";
+}
+
+sub set_speed {
+    my ($self, $F, $comment) = @_;
+    
+    return sprintf "G1 F%.3f%s\n",
+        $F,
+        $self->_comment($comment);
+}
+
+sub travel_to_xy {
+    my ($self, $pointf, $comment) = @_;
+    
+    $self->_pos->set_x($pointf->x);
+    $self->_pos->set_y($pointf->y);     # ))
+    return sprintf "G1 X%.3f Y%.3f F%.3f%s\n",
+        @$pointf,
+        $self->gcode_config->travel_speed*60,
+        $self->_comment($comment);
+}
+
+sub travel_to_xyz {
+    my ($self, $pointf3, $comment) = @_;
+    
+    # If target Z is lower than current Z but higher than nominal Z we
+    # don't perform the Z move but we only move in the XY plane and
+    # adjust the nominal Z by reducing the lift amount that will be 
+    # used for unlift.
+    if (!$self->will_move_z($pointf3->z)) {
+        my $nominal_z = $self->_pos->z - $self->_lifted;
+        $self->_lifted($self->_lifted - ($pointf3->z - $nominal_z));
+        return $self->travel_to_xy(Slic3r::Pointf->new(@$pointf3[X,Y]));
+    }
+    
+    # In all the other cases, we perform an actual XYZ move and cancel
+    # the lift.
+    $self->_lifted(0);
+    return $self->_travel_to_xyz($pointf3, $comment);
+}
+
+sub _travel_to_xyz {
+    my ($self, $pointf3, $comment) = @_;
+    
+    $self->_pos($pointf3);
+    return sprintf "G1 X%.3f Y%.3f Z%.3f F%.3f%s\n",
+        @$pointf3,
+        $self->gcode_config->travel_speed*60,
+        $self->_comment($comment);
+}
+
+sub travel_to_z {
+    my ($self, $z, $comment) = @_;
+    
+    # If target Z is lower than current Z but higher than nominal Z
+    # we don't perform the move but we only adjust the nominal Z by
+    # reducing the lift amount that will be used for unlift.
+    if (!$self->will_move_z($z)) {
+        my $nominal_z = $self->_pos->z - $self->_lifted;
+        $self->_lifted($self->_lifted - ($z - $nominal_z));
+        return "";
+    }
+    
+    # In all the other cases, we perform an actual Z move and cancel
+    # the lift.
+    $self->_lifted(0);
+    return $self->_travel_to_z($z, $comment);
+}
+
+sub _travel_to_z {
+    my ($self, $z, $comment) = @_;
+    
+    $self->_pos->set_z($z);
+    return sprintf "G1 Z%.3f F%.3f%s\n",
+        $z,
+        $self->gcode_config->travel_speed*60,
+        $self->_comment($comment);
+}
+
+sub will_move_z {
+    my ($self, $z) = @_;
+    
+    # If target Z is lower than current Z but higher than nominal Z
+    # we don't perform an actual Z move.
+    if ($self->_lifted > 0) {
+        my $nominal_z = $self->_pos->z - $self->_lifted;
+        if ($z >= $nominal_z && $z <= $self->_pos->z) {
+            return 0;
+        }
+    }
+    return 1;
+}
+
+sub extrude_to_xy {
+    my ($self, $pointf, $dE, $comment) = @_;
+    
+    $self->_pos->set_x($pointf->x);
+    $self->_pos->set_y($pointf->y);     # ))
+    $self->_extruder->extrude($dE);
+    return sprintf "G1 X%.3f Y%.3f %s%.5f%s\n",
+        @$pointf,
+        $self->_extrusion_axis,
+        $self->_extruder->E,
+        $self->_comment($comment);
+}
+
+sub extrude_to_xyz {
+    my ($self, $pointf3, $dE, $comment) = @_;
+    
+    $self->_pos($pointf3);
+    $self->_lifted(0);
+    $self->_extruder->extrude($dE);
+    return sprintf "G1 X%.3f Y%.3f Z%.3f %s%.5f%s\n",
+        @$pointf3,
+        $self->_extrusion_axis,
+        $self->_extruder->E,
+        $self->_comment($comment);
+}
+
+sub retract {
+    my ($self) = @_;
+    
+    return $self->_retract(
+        $self->_extruder->retract_length,
+        $self->_extruder->retract_restart_extra,
+        'retract',
+    );
+}
+
+sub retract_for_toolchange {
+    my ($self) = @_;
+    
+    return $self->_retract(
+        $self->_extruder->retract_length_toolchange,
+        $self->_extruder->retract_restart_extra_toolchange,
+        'retract for toolchange',
+    );
+}
+
+sub _retract {
+    my ($self, $length, $restart_extra, $comment) = @_;
+    
+    if ($self->gcode_config->use_firmware_retraction) {
+        return "G10 ; retract\n";
+    }
+    
+    my $gcode = "";
+    my $dE = $self->_extruder->retract($length, $restart_extra);
+    if ($dE != 0) {
+        $gcode = sprintf "G1 %s%.5f F%.3f%s\n",
+            $self->_extrusion_axis,
+            $self->_extruder->E,
+            $self->_extruder->retract_speed_mm_min,
+            $self->_comment($comment . " dE = $dE");
+    }
+    
+    $gcode .= "M103 ; extruder off\n"
+        if $self->gcode_config->gcode_flavor eq 'makerware';
+    
+    return $gcode;
+}
+
+sub unretract {
+    my ($self, $comment) = @_;
+    
+    my $gcode = "";
+    
+    $gcode .= "M101 ; extruder on\n"
+        if $self->gcode_config->gcode_flavor eq 'makerware';
+    
+    if ($self->gcode_config->use_firmware_retraction) {
+        $gcode .= "G11 ; unretract\n";
+        $gcode .= $self->reset_e;
+        return $gcode;
+    }
+    
+    my $dE = $self->_extruder->unretract;
+    if ($dE != 0) {
+        # use G1 instead of G0 because G0 will blend the restart with the previous travel move
+        $gcode .= sprintf "G1 %s%.5f F%.3f%s\n",
+            $self->_extrusion_axis,
+            $self->_extruder->E,
+            $self->_extruder->retract_speed_mm_min,
+            $self->_comment($comment);
+    }
+    
+    return $gcode;
+}
+
+# If this method is called more than once before calling unlift(),
+# it will not perform subsequent lifts, even if Z was raised manually
+# (i.e. with travel_to_z()) and thus _lifted was reduced.
+sub lift {
+    my ($self) = @_;
+    
+    if ($self->_lifted == 0 && $self->gcode_config->retract_lift->[0] > 0) {
+        my $to_lift = $self->gcode_config->retract_lift->[0];
+        $self->_lifted($to_lift);
+        return $self->_travel_to_z($self->_pos->z + $to_lift, 'lift Z');
+    }
+    return "";
+}
+
+sub unlift {
+    my ($self) = @_;
+    
+    my $gcode = "";
+    if ($self->_lifted > 0) {
+        $gcode .= $self->_travel_to_z($self->_pos->z - $self->_lifted, 'restore layer Z');
+        $self->_lifted(0);
+    }
+    return $gcode;
+}
+
+sub has_multiple_extruders {
+    my ($self) = @_;
+    return $self->_multiple_extruders;
+}
+
+sub extruder {
+    my ($self) = @_;
+    return $self->_extruder;
+}
+
+sub extruders {
+    my ($self) = @_;
+    return [ sort { $a->id <=> $b->id } values %{$self->_extruders} ];
+}
+
+1;
diff --git a/lib/Slic3r/GCode/Layer.pm b/lib/Slic3r/GCode/Layer.pm
index 5f3531d6d..2f70a4a4b 100644
--- a/lib/Slic3r/GCode/Layer.pm
+++ b/lib/Slic3r/GCode/Layer.pm
@@ -63,8 +63,7 @@ sub process_layer {
     $self->gcodegen->enable_loop_clipping(!defined $self->spiralvase || !$self->spiralvase->enable);
     
     if (!$self->second_layer_things_done && $layer->id == 1) {
-        for my $extruder_id (sort keys %{$self->extruders}) {
-            my $extruder = $self->extruders->{$extruder_id};
+        for my $extruder (@{$self->extruders}) {
             $gcode .= $self->gcodegen->set_temperature($extruder->temperature, 0, $extruder->id)
                 if $extruder->temperature && $extruder->temperature != $extruder->first_layer_temperature;
         }
@@ -83,7 +82,7 @@ sub process_layer {
     if (((values %{$self->skirt_done}) < $self->print->config->skirt_height || $self->print->config->skirt_height == -1)
         && !$self->skirt_done->{$layer->print_z}) {
         $self->gcodegen->set_shift(@{$self->shift});
-        my @extruder_ids = sort keys %{$self->extruders};
+        my @extruder_ids = map { $_->id } @{$self->extruders};
         $gcode .= $self->gcodegen->set_extruder($extruder_ids[0]);
         # skip skirt if we have a large brim
         if ($layer->id < $self->print->config->skirt_height || $self->print->config->skirt_height == -1) {
@@ -136,7 +135,7 @@ sub process_layer {
         
         # tweak region ordering to save toolchanges
         my @region_ids = 0 .. ($self->print->region_count-1);
-        if ($self->gcodegen->multiple_extruders) {
+        if ($self->gcodegen->has_multiple_extruders) {
             my $last_extruder = $self->gcodegen->extruder;
             my $best_region_id = first { $self->print->regions->[$_]->config->perimeter_extruder-1 eq $last_extruder } @region_ids;
             @region_ids = ($best_region_id, grep $_ != $best_region_id, @region_ids) if $best_region_id;
@@ -176,7 +175,7 @@ sub process_layer {
                 # give priority to infill if we were already using its extruder and it wouldn't
                 # be good for perimeters
                 if ($self->print->config->infill_first
-                    || ($self->gcodegen->multiple_extruders && $region->config->infill_extruder-1 == $self->gcodegen->extruder->id && $region->config->infill_extruder != $region->config->perimeter_extruder)) {
+                    || ($self->gcodegen->has_multiple_extruders && $region->config->infill_extruder-1 == $self->gcodegen->extruder->id && $region->config->infill_extruder != $region->config->perimeter_extruder)) {
                     $gcode .= $self->_extrude_infill($infill_by_island[$i], $region);
                     $gcode .= $self->_extrude_perimeters($perimeters_by_island[$i], $region);
                 } else {
diff --git a/lib/Slic3r/GCode/OozePrevention.pm b/lib/Slic3r/GCode/OozePrevention.pm
new file mode 100644
index 000000000..5533d2ea0
--- /dev/null
+++ b/lib/Slic3r/GCode/OozePrevention.pm
@@ -0,0 +1,48 @@
+package Slic3r::GCode::OozePrevention;
+use Moo;
+
+use Slic3r::Geometry qw(scale);
+
+has 'standby_points'    => (is => 'rw', required => 1);
+
+sub pre_toolchange {
+    my ($self, $gcodegen) = @_;
+    
+    my $gcode = "";
+    
+    # move to the nearest standby point
+    if (@{$self->standby_points}) {
+        my $last_pos = $gcodegen->last_pos->clone;
+        $last_pos->translate(scale +$gcodegen->shift_x, scale +$gcodegen->shift_y);
+        my $standby_point = $last_pos->nearest_point($self->standby_points);
+        $standby_point->translate(scale -$gcodegen->shift_x, scale -$gcodegen->shift_y);
+        $gcode .= $gcodegen->travel_to($standby_point);
+    }
+    
+    if ($gcodegen->config->standby_temperature_delta != 0) {
+        my $temp = defined $gcodegen->layer && $gcodegen->layer->id == 0
+            ? $gcodegen->_extruder->first_layer_temperature
+            : $gcodegen->_extruder->temperature;
+        # we assume that heating is always slower than cooling, so no need to block
+        $gcode .= $gcodegen->set_temperature($temp + $gcodegen->config->standby_temperature_delta, 0);
+    }
+    
+    return $gcode;
+}
+
+sub post_toolchange {
+    my ($self, $gcodegen) = @_;
+    
+    my $gcode = "";
+    
+    if ($gcodegen->config->standby_temperature_delta != 0) {
+        my $temp = defined $gcodegen->layer && $gcodegen->layer->id == 0
+            ? $gcodegen->_extruder->first_layer_temperature
+            : $gcodegen->_extruder->temperature;
+        $gcode .= $gcodegen->set_temperature($temp, 1);
+    }
+    
+    return $gcode;
+}
+
+1;
diff --git a/lib/Slic3r/Point.pm b/lib/Slic3r/Point.pm
index 6ec4e60bc..abb7a5edf 100644
--- a/lib/Slic3r/Point.pm
+++ b/lib/Slic3r/Point.pm
@@ -7,4 +7,13 @@ sub new_scale {
     return $class->new(map Slic3r::Geometry::scale($_), @_);
 }
 
+package Slic3r::Pointf;
+use strict;
+use warnings;
+
+sub new_unscale {
+    my $class = shift;
+    return $class->new(map Slic3r::Geometry::unscale($_), @_);
+}
+
 1;
diff --git a/lib/Slic3r/Print.pm b/lib/Slic3r/Print.pm
index 4c3a04107..4234f57df 100644
--- a/lib/Slic3r/Print.pm
+++ b/lib/Slic3r/Print.pm
@@ -773,8 +773,8 @@ sub write_gcode {
         placeholder_parser  => $self->placeholder_parser,
         layer_count         => $layer_count,
     );
-    $gcodegen->config->apply_print_config($self->config);
-    $gcodegen->set_extruders($self->extruders, $self->config);
+    $gcodegen->apply_print_config($self->config);
+    $gcodegen->set_extruders($self->extruders);
     
     print $fh "G21 ; set units to millimeters\n" if $self->config->gcode_flavor ne 'makerware';
     print $fh $gcodegen->set_fan(0, 1) if $self->config->cooling && $self->config->disable_fan_first_layers;
@@ -842,7 +842,11 @@ sub write_gcode {
                 $s->translate(map scale($_), @{$self->config->get_at('extruder_offset', $extruder_id)});
             }
             my $convex_hull = convex_hull([ map @$_, @skirts ]);
-            $gcodegen->standby_points([ map $_->clone, map @$_, map $_->subdivide(scale 10), @{offset([$convex_hull], scale 3)} ]);
+            
+            my $oozeprev = Slic3r::GCode::OozePrevention->new(
+                standby_points => [ map $_->clone, map @$_, map $_->subdivide(scale 10), @{offset([$convex_hull], scale 3)} ],
+            );
+            $gcodegen->ooze_prevention($oozeprev);
         }
     }
     
@@ -935,14 +939,13 @@ sub write_gcode {
     }
     
     # write end commands to file
-    print $fh $gcodegen->retract if $gcodegen->extruder;  # empty prints don't even set an extruder
+    print $fh $gcodegen->retract;
     print $fh $gcodegen->set_fan(0);
     printf $fh "%s\n", $gcodegen->placeholder_parser->process($self->config->end_gcode);
     
     $self->total_used_filament(0);
     $self->total_extruded_volume(0);
-    foreach my $extruder_id (@{$self->extruders}) {
-        my $extruder = $gcodegen->extruders->{$extruder_id};
+    foreach my $extruder (@{$gcodegen->extruders}) {
         # the final retraction doesn't really count as "used filament"
         my $used_filament = $extruder->absolute_E + $extruder->retract_length;
         my $extruded_volume = $extruder->extruded_volume($used_filament);
diff --git a/t/retraction.t b/t/retraction.t
index b86255dfc..6c96abd62 100644
--- a/t/retraction.t
+++ b/t/retraction.t
@@ -17,7 +17,7 @@ use Slic3r::Test qw(_eq);
     my $test = sub {
         my ($conf) = @_;
         $conf ||= $config;
-    
+        
         my $print = Slic3r::Test::init_print('20mm_cube', config => $conf, duplicate => $duplicate);
     
         my $tool = 0;
@@ -78,7 +78,7 @@ use Slic3r::Test qw(_eq);
                         $expected_amount = $print->print->config->get_at('retract_length_toolchange', $tool) + $print->print->config->get_at('retract_restart_extra_toolchange', $tool);
                         $changed_tool = 0;
                     }
-                    fail 'unretracted by the correct amount'
+                    fail 'unretracted by the correct amount' && exit
                         if !_eq($info->{dist_E}, $expected_amount);
                     $retracted[$tool] = 0;
                     $retracted_length[$tool] = 0;
diff --git a/xs/src/libslic3r/Extruder.cpp b/xs/src/libslic3r/Extruder.cpp
index d327276f8..d3919e5e4 100644
--- a/xs/src/libslic3r/Extruder.cpp
+++ b/xs/src/libslic3r/Extruder.cpp
@@ -21,13 +21,49 @@ Extruder::reset()
 double
 Extruder::extrude(double dE)
 {
-    if (this->config->use_relative_e_distances) {
+    // in case of relative E distances we always reset to 0 before any output
+    if (this->config->use_relative_e_distances)
         this->E = 0;
-    }
 
     this->E += dE;
     this->absolute_E += dE;
-    return this->E;
+    return dE;
+}
+
+/* This method makes sure the extruder is retracted by the specified amount
+   of filament and returns the amount of filament retracted.
+   If the extruder is already retracted by the same or a greater amount, 
+   this method is a no-op.
+   The restart_extra argument sets the extra length to be used for
+   unretraction. If we're actually performing a retraction, any restart_extra
+   value supplied will overwrite the previous one if any. */
+double
+Extruder::retract(double length, double restart_extra)
+{
+    // in case of relative E distances we always reset to 0 before any output
+    if (this->config->use_relative_e_distances)
+        this->E = 0;
+    
+    double to_retract = length - this->retracted;
+    if (to_retract > 0) {
+        this->E -= to_retract;
+        this->absolute_E -= to_retract;
+        this->retracted += to_retract;
+        this->restart_extra = restart_extra;
+        return to_retract;
+    } else {
+        return 0;
+    }
+}
+
+double
+Extruder::unretract()
+{
+    double dE = this->retracted + this->restart_extra;
+    this->extrude(dE);
+    this->retracted = 0;
+    this->restart_extra = 0;
+    return dE;
 }
 
 Pointf
diff --git a/xs/src/libslic3r/Extruder.hpp b/xs/src/libslic3r/Extruder.hpp
index 9caa38c89..99182c58a 100644
--- a/xs/src/libslic3r/Extruder.hpp
+++ b/xs/src/libslic3r/Extruder.hpp
@@ -14,7 +14,8 @@ class Extruder
     virtual ~Extruder() {}
     void reset();
     double extrude(double dE);
-    
+    double retract(double length, double restart_extra);
+    double unretract();
     
     Pointf extruder_offset() const;
     double nozzle_diameter() const;
diff --git a/xs/src/libslic3r/ExtrusionEntity.cpp b/xs/src/libslic3r/ExtrusionEntity.cpp
index fd39fdc9f..725693fae 100644
--- a/xs/src/libslic3r/ExtrusionEntity.cpp
+++ b/xs/src/libslic3r/ExtrusionEntity.cpp
@@ -123,7 +123,11 @@ ExtrusionPath::gcode(Extruder* extruder, double e, double F,
         const double line_length = line_it->length() * SCALING_FACTOR;
 
         // calculate extrusion length for this line
-        double E = (e == 0) ? 0 : extruder->extrude(e * line_length);
+        double E = 0;
+        if (e > 0) {
+            extruder->extrude(e * line_length);
+            E = extruder->E;
+        }
 
         // compose G-code line
 
diff --git a/xs/src/libslic3r/PrintConfig.cpp b/xs/src/libslic3r/PrintConfig.cpp
index 3486afc22..f5b277134 100644
--- a/xs/src/libslic3r/PrintConfig.cpp
+++ b/xs/src/libslic3r/PrintConfig.cpp
@@ -960,6 +960,7 @@ t_optiondef_map PrintConfigDef::def = PrintConfigDef::build_def();
 REGISTER_CLASS(DynamicPrintConfig, "Config");
 REGISTER_CLASS(PrintObjectConfig, "Config::PrintObject");
 REGISTER_CLASS(PrintRegionConfig, "Config::PrintRegion");
+REGISTER_CLASS(GCodeConfig, "Config::GCode");
 REGISTER_CLASS(PrintConfig, "Config::Print");
 REGISTER_CLASS(FullPrintConfig, "Config::Full");
 #endif
diff --git a/xs/src/libslic3r/PrintConfig.hpp b/xs/src/libslic3r/PrintConfig.hpp
index cdc3d7173..29bfe6646 100644
--- a/xs/src/libslic3r/PrintConfig.hpp
+++ b/xs/src/libslic3r/PrintConfig.hpp
@@ -306,7 +306,62 @@ class PrintRegionConfig : public virtual StaticPrintConfig
     };
 };
 
-class PrintConfig : public virtual StaticPrintConfig
+class GCodeConfig : public virtual StaticPrintConfig
+{
+    public:
+    ConfigOptionString              extrusion_axis;
+    ConfigOptionBool                gcode_comments;
+    ConfigOptionEnum<GCodeFlavor>   gcode_flavor;
+    ConfigOptionFloats              retract_length;
+    ConfigOptionFloats              retract_length_toolchange;
+    ConfigOptionFloats              retract_lift;
+    ConfigOptionFloats              retract_restart_extra;
+    ConfigOptionFloats              retract_restart_extra_toolchange;
+    ConfigOptionInts                retract_speed;
+    ConfigOptionFloat               travel_speed;
+    ConfigOptionBool                use_firmware_retraction;
+    ConfigOptionBool                use_relative_e_distances;
+    
+    GCodeConfig() : StaticPrintConfig() {
+        this->extrusion_axis.value                               = "E";
+        this->gcode_comments.value                               = false;
+        this->gcode_flavor.value                                 = gcfRepRap;
+        this->retract_length.values.resize(1);
+        this->retract_length.values[0]                           = 1;
+        this->retract_length_toolchange.values.resize(1);
+        this->retract_length_toolchange.values[0]                = 10;
+        this->retract_lift.values.resize(1);
+        this->retract_lift.values[0]                             = 0;
+        this->retract_restart_extra.values.resize(1);
+        this->retract_restart_extra.values[0]                    = 0;
+        this->retract_restart_extra_toolchange.values.resize(1);
+        this->retract_restart_extra_toolchange.values[0]         = 0;
+        this->retract_speed.values.resize(1);
+        this->retract_speed.values[0]                            = 30;
+        this->travel_speed.value                                 = 130;
+        this->use_firmware_retraction.value                      = false;
+        this->use_relative_e_distances.value                     = false;
+    };
+    
+    ConfigOption* option(const t_config_option_key opt_key, bool create = false) {
+        if (opt_key == "extrusion_axis")                             return &this->extrusion_axis;
+        if (opt_key == "gcode_comments")                             return &this->gcode_comments;
+        if (opt_key == "gcode_flavor")                               return &this->gcode_flavor;
+        if (opt_key == "retract_length")                             return &this->retract_length;
+        if (opt_key == "retract_length_toolchange")                  return &this->retract_length_toolchange;
+        if (opt_key == "retract_lift")                               return &this->retract_lift;
+        if (opt_key == "retract_restart_extra")                      return &this->retract_restart_extra;
+        if (opt_key == "retract_restart_extra_toolchange")           return &this->retract_restart_extra_toolchange;
+        if (opt_key == "retract_speed")                              return &this->retract_speed;
+        if (opt_key == "travel_speed")                               return &this->travel_speed;
+        if (opt_key == "use_firmware_retraction")                    return &this->use_firmware_retraction;
+        if (opt_key == "use_relative_e_distances")                   return &this->use_relative_e_distances;
+        
+        return NULL;
+    };
+};
+
+class PrintConfig : public GCodeConfig
 {
     public:
     ConfigOptionBool                avoid_crossing_perimeters;
@@ -324,7 +379,6 @@ class PrintConfig : public virtual StaticPrintConfig
     ConfigOptionFloat               extruder_clearance_height;
     ConfigOptionFloat               extruder_clearance_radius;
     ConfigOptionPoints              extruder_offset;
-    ConfigOptionString              extrusion_axis;
     ConfigOptionFloats              extrusion_multiplier;
     ConfigOptionBool                fan_always_on;
     ConfigOptionInt                 fan_below_layer_time;
@@ -336,8 +390,6 @@ class PrintConfig : public virtual StaticPrintConfig
     ConfigOptionInts                first_layer_temperature;
     ConfigOptionBool                g0;
     ConfigOptionBool                gcode_arcs;
-    ConfigOptionBool                gcode_comments;
-    ConfigOptionEnum<GCodeFlavor>   gcode_flavor;
     ConfigOptionFloat               infill_acceleration;
     ConfigOptionBool                infill_first;
     ConfigOptionString              layer_gcode;
@@ -355,12 +407,6 @@ class PrintConfig : public virtual StaticPrintConfig
     ConfigOptionFloat               resolution;
     ConfigOptionFloats              retract_before_travel;
     ConfigOptionBools               retract_layer_change;
-    ConfigOptionFloats              retract_length;
-    ConfigOptionFloats              retract_length_toolchange;
-    ConfigOptionFloats              retract_lift;
-    ConfigOptionFloats              retract_restart_extra;
-    ConfigOptionFloats              retract_restart_extra_toolchange;
-    ConfigOptionInts                retract_speed;
     ConfigOptionFloat               skirt_distance;
     ConfigOptionInt                 skirt_height;
     ConfigOptionInt                 skirts;
@@ -371,14 +417,11 @@ class PrintConfig : public virtual StaticPrintConfig
     ConfigOptionInts                temperature;
     ConfigOptionInt                 threads;
     ConfigOptionString              toolchange_gcode;
-    ConfigOptionFloat               travel_speed;
-    ConfigOptionBool                use_firmware_retraction;
-    ConfigOptionBool                use_relative_e_distances;
     ConfigOptionFloat               vibration_limit;
     ConfigOptionBools               wipe;
     ConfigOptionFloat               z_offset;
     
-    PrintConfig() : StaticPrintConfig() {
+    PrintConfig() : GCodeConfig() {
         this->avoid_crossing_perimeters.value                    = false;
         this->bed_shape.values.push_back(Pointf(0,0));
         this->bed_shape.values.push_back(Pointf(200,0));
@@ -398,7 +441,6 @@ class PrintConfig : public virtual StaticPrintConfig
         this->extruder_clearance_radius.value                    = 20;
         this->extruder_offset.values.resize(1);
         this->extruder_offset.values[0]                          = Pointf(0,0);
-        this->extrusion_axis.value                               = "E";
         this->extrusion_multiplier.values.resize(1);
         this->extrusion_multiplier.values[0]                     = 1;
         this->fan_always_on.value                                = false;
@@ -415,8 +457,6 @@ class PrintConfig : public virtual StaticPrintConfig
         this->first_layer_temperature.values[0]                  = 200;
         this->g0.value                                           = false;
         this->gcode_arcs.value                                   = false;
-        this->gcode_comments.value                               = false;
-        this->gcode_flavor.value                                 = gcfRepRap;
         this->infill_acceleration.value                          = 0;
         this->infill_first.value                                 = false;
         this->layer_gcode.value                                  = "";
@@ -436,18 +476,6 @@ class PrintConfig : public virtual StaticPrintConfig
         this->retract_before_travel.values[0]                    = 2;
         this->retract_layer_change.values.resize(1);
         this->retract_layer_change.values[0]                     = true;
-        this->retract_length.values.resize(1);
-        this->retract_length.values[0]                           = 1;
-        this->retract_length_toolchange.values.resize(1);
-        this->retract_length_toolchange.values[0]                = 10;
-        this->retract_lift.values.resize(1);
-        this->retract_lift.values[0]                             = 0;
-        this->retract_restart_extra.values.resize(1);
-        this->retract_restart_extra.values[0]                    = 0;
-        this->retract_restart_extra_toolchange.values.resize(1);
-        this->retract_restart_extra_toolchange.values[0]         = 0;
-        this->retract_speed.values.resize(1);
-        this->retract_speed.values[0]                            = 30;
         this->skirt_distance.value                               = 6;
         this->skirt_height.value                                 = 1;
         this->skirts.value                                       = 1;
@@ -459,9 +487,6 @@ class PrintConfig : public virtual StaticPrintConfig
         this->temperature.values[0]                              = 200;
         this->threads.value                                      = 2;
         this->toolchange_gcode.value                             = "";
-        this->travel_speed.value                                 = 130;
-        this->use_firmware_retraction.value                      = false;
-        this->use_relative_e_distances.value                     = false;
         this->vibration_limit.value                              = 0;
         this->wipe.values.resize(1);
         this->wipe.values[0]                                     = false;
@@ -484,7 +509,6 @@ class PrintConfig : public virtual StaticPrintConfig
         if (opt_key == "extruder_clearance_height")                  return &this->extruder_clearance_height;
         if (opt_key == "extruder_clearance_radius")                  return &this->extruder_clearance_radius;
         if (opt_key == "extruder_offset")                            return &this->extruder_offset;
-        if (opt_key == "extrusion_axis")                             return &this->extrusion_axis;
         if (opt_key == "extrusion_multiplier")                       return &this->extrusion_multiplier;
         if (opt_key == "fan_always_on")                              return &this->fan_always_on;
         if (opt_key == "fan_below_layer_time")                       return &this->fan_below_layer_time;
@@ -496,8 +520,6 @@ class PrintConfig : public virtual StaticPrintConfig
         if (opt_key == "first_layer_temperature")                    return &this->first_layer_temperature;
         if (opt_key == "g0")                                         return &this->g0;
         if (opt_key == "gcode_arcs")                                 return &this->gcode_arcs;
-        if (opt_key == "gcode_comments")                             return &this->gcode_comments;
-        if (opt_key == "gcode_flavor")                               return &this->gcode_flavor;
         if (opt_key == "infill_acceleration")                        return &this->infill_acceleration;
         if (opt_key == "infill_first")                               return &this->infill_first;
         if (opt_key == "layer_gcode")                                return &this->layer_gcode;
@@ -515,12 +537,6 @@ class PrintConfig : public virtual StaticPrintConfig
         if (opt_key == "resolution")                                 return &this->resolution;
         if (opt_key == "retract_before_travel")                      return &this->retract_before_travel;
         if (opt_key == "retract_layer_change")                       return &this->retract_layer_change;
-        if (opt_key == "retract_length")                             return &this->retract_length;
-        if (opt_key == "retract_length_toolchange")                  return &this->retract_length_toolchange;
-        if (opt_key == "retract_lift")                               return &this->retract_lift;
-        if (opt_key == "retract_restart_extra")                      return &this->retract_restart_extra;
-        if (opt_key == "retract_restart_extra_toolchange")           return &this->retract_restart_extra_toolchange;
-        if (opt_key == "retract_speed")                              return &this->retract_speed;
         if (opt_key == "skirt_distance")                             return &this->skirt_distance;
         if (opt_key == "skirt_height")                               return &this->skirt_height;
         if (opt_key == "skirts")                                     return &this->skirts;
@@ -531,18 +547,20 @@ class PrintConfig : public virtual StaticPrintConfig
         if (opt_key == "temperature")                                return &this->temperature;
         if (opt_key == "threads")                                    return &this->threads;
         if (opt_key == "toolchange_gcode")                           return &this->toolchange_gcode;
-        if (opt_key == "travel_speed")                               return &this->travel_speed;
-        if (opt_key == "use_firmware_retraction")                    return &this->use_firmware_retraction;
-        if (opt_key == "use_relative_e_distances")                   return &this->use_relative_e_distances;
         if (opt_key == "vibration_limit")                            return &this->vibration_limit;
         if (opt_key == "wipe")                                       return &this->wipe;
         if (opt_key == "z_offset")                                   return &this->z_offset;
         
+        // look in parent class
+        ConfigOption* opt;
+        if ((opt = GCodeConfig::option(opt_key, create)) != NULL) return opt;
+        
         return NULL;
     };
 };
 
-class FullPrintConfig : public PrintObjectConfig, public PrintRegionConfig, public PrintConfig {
+class FullPrintConfig : public PrintObjectConfig, public PrintRegionConfig, public PrintConfig
+{
     public:
     ConfigOption* option(const t_config_option_key opt_key, bool create = false) {
         ConfigOption* opt;
@@ -551,15 +569,6 @@ class FullPrintConfig : public PrintObjectConfig, public PrintRegionConfig, publ
         if ((opt = PrintConfig::option(opt_key, create)) != NULL) return opt;
         return NULL;
     };
-    
-    std::string get_extrusion_axis() {
-        if (this->gcode_flavor == gcfMach3) {
-            return std::string("A");
-        } else if (this->gcode_flavor == gcfNoExtrusion) {
-            return std::string("");
-        }
-        return this->extrusion_axis;
-    }
 };
 
 }
diff --git a/xs/xsp/Config.xsp b/xs/xsp/Config.xsp
index 4c56e10c8..b11533e36 100644
--- a/xs/xsp/Config.xsp
+++ b/xs/xsp/Config.xsp
@@ -28,6 +28,27 @@
     void normalize();
 };
 
+%name{Slic3r::Config::GCode} class GCodeConfig {
+    GCodeConfig();
+    ~GCodeConfig();
+    bool has(t_config_option_key opt_key);
+    SV* as_hash();
+    SV* get(t_config_option_key opt_key);
+    SV* get_at(t_config_option_key opt_key, int i);
+    bool set(t_config_option_key opt_key, SV* value);
+    bool set_deserialize(t_config_option_key opt_key, SV* str);
+    std::string serialize(t_config_option_key opt_key);
+    double get_abs_value(t_config_option_key opt_key);
+    %name{get_abs_value_over}
+        double get_abs_value(t_config_option_key opt_key, double ratio_over);
+    void apply_print_config(PrintConfig* other)
+        %code{% THIS->apply(*other, true); %};
+    void apply_dynamic(DynamicPrintConfig* other)
+        %code{% THIS->apply(*other, true); %};
+    std::vector<std::string> get_keys()
+        %code{% THIS->keys(&RETVAL); %};
+};
+
 %name{Slic3r::Config::Print} class PrintConfig {
     PrintConfig();
     ~PrintConfig();
@@ -112,7 +133,6 @@
         %code{% THIS->apply(*other, true); %};
     std::vector<std::string> get_keys()
         %code{% THIS->keys(&RETVAL); %};
-    std::string get_extrusion_axis();
 };
 
 %package{Slic3r::Config};
diff --git a/xs/xsp/Extruder.xsp b/xs/xsp/Extruder.xsp
index 582b39b99..43bdbfabc 100644
--- a/xs/xsp/Extruder.xsp
+++ b/xs/xsp/Extruder.xsp
@@ -6,10 +6,14 @@
 %}
 
 %name{Slic3r::Extruder} class Extruder {
-    Extruder(int id, PrintConfig *config);
+    // We don't need a Perl constructor with PrintConfig at the moment
+    //Extruder(int id, PrintConfig *config);
+    Extruder(int id, FullPrintConfig *config);
     ~Extruder();
     void reset();
     double extrude(double dE);
+    double retract(double length, double restart_extra);
+    double unretract();
     
     int id() const
         %code%{ RETVAL = THIS->id; %};
diff --git a/xs/xsp/Point.xsp b/xs/xsp/Point.xsp
index 774b2fc1a..e1163ea5c 100644
--- a/xs/xsp/Point.xsp
+++ b/xs/xsp/Point.xsp
@@ -110,4 +110,10 @@ Point::coincides_with(point_sv)
         %code{% RETVAL = THIS->y; %};
     double z()
         %code{% RETVAL = THIS->z; %};
+    void set_x(double val)
+        %code{% THIS->x = val; %};
+    void set_y(double val)
+        %code{% THIS->y = val; %};
+    void set_z(double val)
+        %code{% THIS->z = val; %};
 };
diff --git a/xs/xsp/my.map b/xs/xsp/my.map
index a7264c62e..41476ca2c 100644
--- a/xs/xsp/my.map
+++ b/xs/xsp/my.map
@@ -29,6 +29,9 @@ Ref<PrintObjectConfig>     O_OBJECT_SLIC3R_T
 PrintRegionConfig*         O_OBJECT_SLIC3R
 Ref<PrintRegionConfig>     O_OBJECT_SLIC3R_T
 
+GCodeConfig*               O_OBJECT_SLIC3R
+Ref<GCodeConfig>           O_OBJECT_SLIC3R_T
+
 PrintConfig*               O_OBJECT_SLIC3R
 Ref<PrintConfig>           O_OBJECT_SLIC3R_T
 
diff --git a/xs/xsp/typemap.xspt b/xs/xsp/typemap.xspt
index 57c321bb4..87283debf 100644
--- a/xs/xsp/typemap.xspt
+++ b/xs/xsp/typemap.xspt
@@ -40,6 +40,8 @@
 %typemap{Ref<PrintObjectConfig>}{simple};
 %typemap{PrintRegionConfig*};
 %typemap{Ref<PrintRegionConfig>}{simple};
+%typemap{GCodeConfig*};
+%typemap{Ref<GCodeConfig>}{simple};
 %typemap{PrintConfig*};
 %typemap{Ref<PrintConfig>}{simple};
 %typemap{FullPrintConfig*};