diff --git a/lib/Slic3r/GUI/Plater.pm b/lib/Slic3r/GUI/Plater.pm
index 1e229a78..0213f6c4 100644
--- a/lib/Slic3r/GUI/Plater.pm
+++ b/lib/Slic3r/GUI/Plater.pm
@@ -719,11 +719,11 @@ sub make_model {
         $new_model_object->scale($plater_object->scale);
         $new_model_object->add_instance(
             rotation    => $plater_object->rotate,  # around center point
-            offset      => [ @$_ ],
+            offset      => Slic3r::Point->new($_),
         ) for @{$plater_object->instances};
-        $new_model_object->align_to_origin;
     }
     
+    $model->align_to_origin;
     return $model;
 }
 
diff --git a/lib/Slic3r/Model.pm b/lib/Slic3r/Model.pm
index 70824726..b7ff6f7a 100644
--- a/lib/Slic3r/Model.pm
+++ b/lib/Slic3r/Model.pm
@@ -164,14 +164,19 @@ sub vertices {
     return [ map @{$_->vertices}, @{$self->objects} ];
 }
 
+sub used_vertices {
+    my $self = shift;
+    return [ map @{$_->used_vertices}, @{$self->objects} ];
+}
+
 sub size {
     my $self = shift;
-    return [ Slic3r::Geometry::size_3D($self->vertices) ];
+    return [ Slic3r::Geometry::size_3D($self->used_vertices) ];
 }
 
 sub extents {
     my $self = shift;
-    return Slic3r::Geometry::bounding_box_3D($self->vertices);
+    return Slic3r::Geometry::bounding_box_3D($self->used_vertices);
 }
 
 sub align_to_origin {
@@ -179,8 +184,17 @@ sub align_to_origin {
     
     # calculate the displacements needed to 
     # have lowest value for each axis at coordinate 0
-    my @extents = $self->extents;
-    $self->move(map -$extents[$_][MIN], X,Y,Z);
+    {
+        my @extents = $self->extents;
+        $self->move(map -$extents[$_][MIN], X,Y,Z);
+    }
+    
+    # align all instances to 0,0 as well
+    {
+        my @instances = map @{$_->instances}, @{$self->objects};
+        my @extents = Slic3r::Geometry::bounding_box_3D([ map $_->offset, @instances ]);
+        $_->offset->translate(-$extents[X][MIN], -$extents[Y][MIN]) for @instances;
+    }
 }
 
 sub move {
@@ -260,7 +274,7 @@ package Slic3r::Model::Object;
 use Moo;
 
 use List::Util qw(first);
-use Slic3r::Geometry qw(X Y Z MIN move_points_3D);
+use Slic3r::Geometry qw(X Y Z MIN move_points move_points_3D);
 use Storable qw(dclone);
 
 has 'input_file' => (is => 'rw');
@@ -309,14 +323,19 @@ sub mesh {
     );
 }
 
+sub used_vertices {
+    my $self = shift;
+    return [ map $self->vertices->[$_], map @$_, map @{$_->facets}, @{$self->volumes} ];
+}
+
 sub size {
     my $self = shift;
-    return [ Slic3r::Geometry::size_3D($self->vertices) ];
+    return [ Slic3r::Geometry::size_3D($self->used_vertices) ];
 }
 
 sub extents {
     my $self = shift;
-    return Slic3r::Geometry::bounding_box_3D($self->vertices);
+    return Slic3r::Geometry::bounding_box_3D($self->used_vertices);
 }
 
 sub align_to_origin {
@@ -391,6 +410,6 @@ use Moo;
 
 has 'object'    => (is => 'ro', weak_ref => 1, required => 1);
 has 'rotation'  => (is => 'rw', default => sub { 0 });  # around mesh center point
-has 'offset'    => (is => 'rw');
+has 'offset'    => (is => 'rw');  # must be Slic3r::Point object
 
 1;
diff --git a/lib/Slic3r/Print.pm b/lib/Slic3r/Print.pm
index ae299248..84a208ea 100644
--- a/lib/Slic3r/Print.pm
+++ b/lib/Slic3r/Print.pm
@@ -6,7 +6,7 @@ use File::Spec;
 use List::Util qw(max first);
 use Math::ConvexHull::MonotoneChain qw(convex_hull);
 use Slic3r::ExtrusionPath ':roles';
-use Slic3r::Geometry qw(X Y Z X1 Y1 X2 Y2 MIN PI scale unscale move_points nearest_point);
+use Slic3r::Geometry qw(X Y Z X1 Y1 X2 Y2 MIN MAX PI scale unscale move_points nearest_point);
 use Slic3r::Geometry::Clipper qw(diff_ex union_ex union_pt intersection_ex offset
     offset2 traverse_pt JT_ROUND JT_SQUARE PFT_EVENODD);
 use Time::HiRes qw(gettimeofday tv_interval);
@@ -116,8 +116,7 @@ sub add_model {
                 : $mesh;
         }
         
-        foreach my $mesh (@meshes) {
-            next unless $mesh;
+        foreach my $mesh (grep $_, @meshes) {
             $mesh->check_manifoldness;
             
             # we ignore the per-instance rotation currently and only 
@@ -127,12 +126,22 @@ sub add_model {
             $mesh->scale(1 / &Slic3r::SCALING_FACTOR);
         }
         
+        # align the object to origin; not sure this is required by the toolpath generation
+        # algorithms, but it's good practice to avoid negative coordinates; it probably 
+        # provides also some better performance in infill generation
+        my @extents = Slic3r::Geometry::bounding_box_3D([ map @{$_->used_vertices}, grep $_, @meshes ]);
+        foreach my $mesh (grep $_, @meshes) {
+            $mesh->move(map -$extents[$_][MIN], X,Y,Z);
+        }
+        
         # initialize print object
         push @{$self->objects}, Slic3r::Print::Object->new(
             print       => $self,
             meshes      => [ @meshes ],
-            copies      => [ map [ scale $_->offset->[X], scale $_->offset->[Y] ], @{$object->instances} ],
-            size        => [ map scale $_, @{ $object->size } ],
+            copies      => [
+                map [ (scale $_->offset->[X]) + $extents[X][MIN], (scale $_->offset->[Y]) + $extents[Y][MIN] ], @{$object->instances},
+            ],
+            size        => [ map $extents[$_][MAX] - $extents[$_][MIN], (X,Y,Z) ],
             input_file  => $object->input_file,
             layer_height_ranges => $object->layer_height_ranges,
         );
diff --git a/lib/Slic3r/TriangleMesh.pm b/lib/Slic3r/TriangleMesh.pm
index f6146d54..3506d893 100644
--- a/lib/Slic3r/TriangleMesh.pm
+++ b/lib/Slic3r/TriangleMesh.pm
@@ -398,14 +398,19 @@ sub duplicate {
     $self->BUILD;
 }
 
+sub used_vertices {
+    my $self = shift;
+    return [ map $self->vertices->[$_], map @$_, @{$self->facets} ];
+}
+
 sub extents {
     my $self = shift;
-    return Slic3r::Geometry::bounding_box_3D($self->vertices);
+    return Slic3r::Geometry::bounding_box_3D($self->used_vertices);
 }
 
 sub size {
     my $self = shift;
-    return Slic3r::Geometry::size_3D($self->vertices);
+    return Slic3r::Geometry::size_3D($self->used_vertices);
 }
 
 sub slice_facet {