diff --git a/MANIFEST b/MANIFEST
index 36389aef1..b2fe05eda 100644
--- a/MANIFEST
+++ b/MANIFEST
@@ -30,6 +30,7 @@ lib/Slic3r/GCode/MotionPlanner.pm
 lib/Slic3r/GCode/Reader.pm
 lib/Slic3r/GCode/SpiralVase.pm
 lib/Slic3r/Geometry.pm
+lib/Slic3r/Geometry/BoundingBox.pm
 lib/Slic3r/Geometry/Clipper.pm
 lib/Slic3r/GUI.pm
 lib/Slic3r/GUI/AboutDialog.pm
diff --git a/lib/Slic3r.pm b/lib/Slic3r.pm
index 1338ce066..67314e217 100644
--- a/lib/Slic3r.pm
+++ b/lib/Slic3r.pm
@@ -51,6 +51,8 @@ use Slic3r::GCode::MotionPlanner;
 use Slic3r::GCode::Reader;
 use Slic3r::GCode::SpiralVase;
 use Slic3r::Geometry qw(PI);
+use Slic3r::Geometry::BoundingBox;
+use Slic3r::Geometry::Clipper;
 use Slic3r::Layer;
 use Slic3r::Layer::Region;
 use Slic3r::Line;
diff --git a/lib/Slic3r/ExPolygon.pm b/lib/Slic3r/ExPolygon.pm
index 45b59acec..5190357f3 100644
--- a/lib/Slic3r/ExPolygon.pm
+++ b/lib/Slic3r/ExPolygon.pm
@@ -335,11 +335,25 @@ sub align_to_origin {
     
     my @bb = Slic3r::Geometry::bounding_box([ map @$_, map @$_, @{$self->expolygons} ]);
     $_->translate(-$bb[X1], -$bb[Y1]) for @{$self->expolygons};
+    $self;
+}
+
+sub scale {
+    my $self = shift;
+    $_->scale(@_) for @{$self->expolygons};
+    $self;
 }
 
 sub rotate {
     my $self = shift;
     $_->rotate(@_) for @{$self->expolygons};
+    $self;
+}
+
+sub translate {
+    my $self = shift;
+    $_->translate(@_) for @{$self->expolygons};
+    $self;
 }
 
 sub size {
diff --git a/lib/Slic3r/GUI/Plater.pm b/lib/Slic3r/GUI/Plater.pm
index dc17bdcf8..7b5dde5bb 100644
--- a/lib/Slic3r/GUI/Plater.pm
+++ b/lib/Slic3r/GUI/Plater.pm
@@ -452,7 +452,7 @@ sub arrange {
     my $total_parts = sum(map $_->instances_count, @{$self->{objects}}) or return;
     my @size = ();
     for my $a (X,Y) {
-        $size[$a] = max(map $_->size->[$a], @{$self->{objects}});
+        $size[$a] = max(map $_->transformed_size->[$a], @{$self->{objects}});
     }
     
     eval {
@@ -769,10 +769,9 @@ sub recenter {
     my @print_bb = Slic3r::Geometry::bounding_box([
         map {
             my $obj = $_;
-            map {
-                my $instance = $_;
-                $instance, [ map $instance->[$_] + $obj->size->[$_], X,Y ];
-            } @{$obj->instances};
+            my $bb = $obj->transformed_bounding_box;
+            my @points = ($bb->min_point, $bb->max_point);
+            map Slic3r::Geometry::move_points($_, @points), @{$obj->instances};
         } @{$self->{objects}},
     ]);
     $self->{shift} = [
@@ -867,9 +866,12 @@ sub repaint {
         next unless $object->thumbnail && @{$object->thumbnail->expolygons};
         for my $instance_idx (0 .. $#{$object->instances}) {
             my $instance = $object->instances->[$instance_idx];
-            push @{$parent->{object_previews}}, [ $obj_idx, $instance_idx, $object->thumbnail->clone ];
-            $_->translate(map $parent->to_pixel($instance->[$_]) + $parent->{shift}[$_], (X,Y))
-            	for @{$parent->{object_previews}->[-1][2]->expolygons};
+            
+            my $thumbnail = $object->thumbnail
+                ->clone
+                ->translate(map $parent->to_pixel($instance->[$_]) + $parent->{shift}[$_], (X,Y));
+            
+            push @{$parent->{object_previews}}, [ $obj_idx, $instance_idx, $thumbnail ];
             
             my $drag_object = $self->{drag_object};
             if (defined $drag_object && $obj_idx == $drag_object->[0] && $instance_idx == $drag_object->[1]) {
@@ -1065,15 +1067,15 @@ package Slic3r::GUI::Plater::Object;
 use Moo;
 
 use Math::ConvexHull::MonotoneChain qw(convex_hull);
-use Slic3r::Geometry qw(X Y Z);
+use Slic3r::Geometry qw(X Y Z MIN MAX deg2rad);
 
 has 'name'                  => (is => 'rw', required => 1);
 has 'input_file'            => (is => 'rw', required => 1);
 has 'input_file_object_id'  => (is => 'rw');  # undef means keep model object
 has 'model_object'          => (is => 'rw', required => 1, trigger => 1);
-has 'size'                  => (is => 'rw');
+has 'bounding_box'          => (is => 'rw');  # 3D bb of original object (aligned to origin) with no rotation or scaling
 has 'scale'                 => (is => 'rw', default => sub { 1 });
-has 'rotate'                => (is => 'rw', default => sub { 0 });
+has 'rotate'                => (is => 'rw', default => sub { 0 }); # around object center point
 has 'instances'             => (is => 'rw', default => sub { [] }); # upward Y axis
 has 'thumbnail'             => (is => 'rw');
 has 'thumbnail_scaling_factor' => (is => 'rw');
@@ -1088,8 +1090,9 @@ has 'is_manifold'           => (is => 'rw');
 sub _trigger_model_object {
     my $self = shift;
     if ($self->model_object) {
+        $self->model_object->align_to_origin;
     	my $mesh = $self->model_object->mesh;
-	    $self->size([$mesh->size]);
+	    $self->bounding_box($mesh->bounding_box);
 	    $self->facets(scalar @{$mesh->facets});
 	    $self->vertices(scalar @{$mesh->vertices});
 	    $self->materials($self->model_object->materials_count);
@@ -1131,22 +1134,22 @@ sub make_thumbnail {
     my $self = shift;
     
     my $mesh = $self->model_object->mesh;
+    $mesh->align_to_origin;
     my $thumbnail = Slic3r::ExPolygon::Collection->new(
     	expolygons => (@{$mesh->facets} <= 5000)
     		? $mesh->horizontal_projection
     		: [ Slic3r::ExPolygon->new(convex_hull($mesh->vertices)) ],
     );
-    for (map @$_, map @$_, @{$thumbnail->expolygons}) {
-        @$_ = map $_ * $self->thumbnail_scaling_factor, @$_;
-    }
+    $thumbnail->scale($self->thumbnail_scaling_factor);
+    
     # only simplify expolygons larger than the threshold
-    @{$thumbnail->expolygons} = map { ($_->area >= 1) ? $_->simplify(0.5) : $_ } @{$thumbnail->expolygons};
-    foreach my $expolygon (@{$thumbnail->expolygons}) {
-    	$expolygon->rotate(Slic3r::Geometry::deg2rad($self->rotate));
-    	$expolygon->scale($self->scale);
-    }
-    @{$thumbnail->expolygons} = grep @$_, @{$thumbnail->expolygons};
-    $thumbnail->align_to_origin;
+    @{$thumbnail->expolygons} = grep @$_,
+        map { ($_->area >= 1) ? $_->simplify(0.5) : $_ }
+        @{$thumbnail->expolygons};
+    
+    $thumbnail->rotate(deg2rad($self->rotate));  # TODO: around center
+    $thumbnail->scale($self->scale);
+    
     $self->thumbnail($thumbnail);  # ignored in multi-threaded environments
     $self->free_model_object;
     
@@ -1158,10 +1161,8 @@ sub set_rotation {
     my ($angle) = @_;
     
     if ($self->thumbnail) {
-        $self->thumbnail->rotate(Slic3r::Geometry::deg2rad($angle - $self->rotate));
-        $self->thumbnail->align_to_origin;
-        my $z_size = $self->size->[Z];
-        $self->size([ (map $_ / $self->thumbnail_scaling_factor, @{$self->thumbnail->size}), $z_size ]);
+        # rotate around object centerpoint
+        $self->thumbnail->rotate(deg2rad($angle - $self->rotate), $self->bounding_box->center_2D->clone->scale($self->thumbnail_scaling_factor));
     }
     $self->rotate($angle);
 }
@@ -1170,14 +1171,25 @@ sub set_scale {
     my $self = shift;
     my ($scale) = @_;
     
-    my $factor = $scale / $self->scale;
-    return if $factor == 1;
-    $self->size->[$_] *= $factor for X,Y,Z;
     if ($self->thumbnail) {
-	    $_->scale($factor) for @{$self->thumbnail->expolygons};
-		$self->thumbnail->align_to_origin;
+	    $self->thumbnail->scale($scale / $self->scale);
     }
     $self->scale($scale);
 }
 
+# bounding box with applied rotation and scaling
+sub transformed_bounding_box {
+    my $self = shift;
+    
+    return $self->bounding_box
+        ->clone
+        ->rotate(deg2rad($self->rotate), $self->bounding_box->center)
+        ->scale($self->scale);
+}
+
+sub transformed_size {
+    my $self = shift;
+    return $self->transformed_bounding_box->size;
+}
+
 1;
diff --git a/lib/Slic3r/GUI/Plater/ObjectDialog.pm b/lib/Slic3r/GUI/Plater/ObjectDialog.pm
index 3cb725e64..4fc838841 100644
--- a/lib/Slic3r/GUI/Plater/ObjectDialog.pm
+++ b/lib/Slic3r/GUI/Plater/ObjectDialog.pm
@@ -78,7 +78,7 @@ sub get_properties {
 	my $object = $self->{object};
 	return [
 		['Name'			=> $object->name],
-		['Size'			=> sprintf "%.2f x %.2f x %.2f", @{$object->size}],
+		['Size'			=> sprintf "%.2f x %.2f x %.2f", @{$object->transformed_size}],
 		['Facets'		=> $object->facets],
 		['Vertices'		=> $object->vertices],
 		['Materials' 	=> $object->materials],
diff --git a/lib/Slic3r/Geometry/BoundingBox.pm b/lib/Slic3r/Geometry/BoundingBox.pm
new file mode 100644
index 000000000..cbcec824c
--- /dev/null
+++ b/lib/Slic3r/Geometry/BoundingBox.pm
@@ -0,0 +1,78 @@
+package Slic3r::Geometry::BoundingBox;
+use Moo;
+use Slic3r::Geometry qw(X Y Z MIN MAX X1 Y1 X2 Y2);
+use Storable qw();
+
+has 'extents' => (is => 'ro', required => 1);
+
+sub clone { Storable::dclone($_[0]) }
+
+# four-arguments 2D bb
+sub bb {
+    my $self = shift;
+    my $extents = $self->extents;
+    return [ $extents->[X][MIN], $extents->[Y][MIN], $extents->[X][MAX], $extents->[Y][MAX] ];
+}
+
+sub polygon {
+    my $self = shift;
+    return Slic3r::Polygon->new_from_bounding_box($self->bb);
+}
+
+sub rotate {
+    my $self = shift;
+    my ($angle, $center) = @_;
+    
+    # rotate the 2D bounding box polygon and leave Z unaltered
+    my $bb_p = $self->polygon;
+    $bb_p->rotate($angle, $center);
+    my @bb = $bb_p->bounding_box;
+    $self->extents->[X][MIN] = $bb[X1];
+    $self->extents->[Y][MIN] = $bb[Y1];
+    $self->extents->[X][MAX] = $bb[X2];
+    $self->extents->[Y][MAX] = $bb[Y2];
+    
+    $self;
+}
+
+sub scale {
+    my $self = shift;
+    my ($factor) = @_;
+    
+    $_ *= $factor
+        for map @$_[MIN,MAX],
+            grep $_, @{$self->extents}[X,Y,Z];
+    
+    $self;
+}
+
+sub size {
+    my $self = shift;
+    
+    my $extents = $self->extents;
+    return [ map $extents->[$_][MAX] - $extents->[$_][MIN], grep $extents->[$_], (X,Y,Z) ];
+}
+
+sub center {
+    my $self = shift;
+    
+    my $extents = $self->extents;
+    return [ map +($extents->[$_][MAX] + $extents->[$_][MIN])/2, grep $extents->[$_], (X,Y,Z) ];
+}
+
+sub center_2D {
+    my $self = shift;
+    return Slic3r::Point->new(@{$self->center}[X,Y]);
+}
+
+sub min_point {
+    my $self = shift;
+    return Slic3r::Point->new($self->extents->[X][MIN], $self->extents->[Y][MIN]);
+}
+
+sub max_point {
+    my $self = shift;
+    return Slic3r::Point->new($self->extents->[X][MAX], $self->extents->[Y][MAX]);
+}
+
+1;
diff --git a/lib/Slic3r/Point.pm b/lib/Slic3r/Point.pm
index 26e79045a..b820a1e83 100644
--- a/lib/Slic3r/Point.pm
+++ b/lib/Slic3r/Point.pm
@@ -35,6 +35,13 @@ sub distance_to {
     return Slic3r::Geometry::distance_between_points($self, $point);
 }
 
+sub scale {
+    my $self = shift;
+    my ($factor) = @_;
+    $_ *= $factor for @$self;
+    $self;
+}
+
 sub rotate {
     my $self = shift;
     my ($angle, $center) = @_;
diff --git a/lib/Slic3r/TriangleMesh.pm b/lib/Slic3r/TriangleMesh.pm
index 3506d893e..a58f3c0e6 100644
--- a/lib/Slic3r/TriangleMesh.pm
+++ b/lib/Slic3r/TriangleMesh.pm
@@ -408,6 +408,11 @@ sub extents {
     return Slic3r::Geometry::bounding_box_3D($self->used_vertices);
 }
 
+sub bounding_box {
+    my $self = shift;
+    return Slic3r::Geometry::BoundingBox->new(extents => [ $self->extents ]);
+}
+
 sub size {
     my $self = shift;
     return Slic3r::Geometry::size_3D($self->used_vertices);