diff --git a/lib/Slic3r/ExPolygon.pm b/lib/Slic3r/ExPolygon.pm
index 1fa75bb99..9bda96205 100644
--- a/lib/Slic3r/ExPolygon.pm
+++ b/lib/Slic3r/ExPolygon.pm
@@ -10,24 +10,6 @@ use Math::Geometry::Voronoi;
 use Slic3r::Geometry qw(X Y A B point_in_polygon same_line epsilon);
 use Slic3r::Geometry::Clipper qw(union_ex JT_MITER);
 
-sub is_valid {
-    my $self = shift;
-    return (!first { !$_->is_valid } @$self)
-        && $self->contour->is_counter_clockwise
-        && (!first { $_->is_counter_clockwise } @{$self->holes});
-}
-
-# returns false if the expolygon is too tight to be printed
-sub is_printable {
-    my $self = shift;
-    my ($width) = @_;
-    
-    # try to get an inwards offset
-    # for a distance equal to half of the extrusion width;
-    # if no offset is possible, then expolygon is not printable.
-    return @{Slic3r::Geometry::Clipper::offset($self, -$width / 2)} ? 1 : 0;
-}
-
 sub wkt {
     my $self = shift;
     return sprintf "POLYGON(%s)", 
diff --git a/lib/Slic3r/Geometry.pm b/lib/Slic3r/Geometry.pm
index 6a54fa55d..7f231efc5 100644
--- a/lib/Slic3r/Geometry.pm
+++ b/lib/Slic3r/Geometry.pm
@@ -692,17 +692,18 @@ sub _line_intersection2 {
 # 2D
 sub bounding_box {
     my ($points) = @_;
-    
-    my @x = (undef, undef);
-    my @y = (undef, undef);
-    for (@$points) {
-        $x[MIN] = $_->[X] if !defined $x[MIN] || $_->[X] < $x[MIN];
-        $x[MAX] = $_->[X] if !defined $x[MAX] || $_->[X] > $x[MAX];
-        $y[MIN] = $_->[Y] if !defined $y[MIN] || $_->[Y] < $y[MIN];
-        $y[MAX] = $_->[Y] if !defined $y[MAX] || $_->[Y] > $y[MAX];
+    use XXX; ZZZ "not" if ref($points->[0]) eq 'ARRAY';
+    my @x = map $_->x, @$points;
+    my @y = map $_->y, @$points;    #,,
+    my @bb = (undef, undef, undef, undef);
+    for (0..$#x) {
+        $bb[X1] = $x[$_] if !defined $bb[X1] || $x[$_] < $bb[X1];
+        $bb[X2] = $x[$_] if !defined $bb[X2] || $x[$_] > $bb[X2];
+        $bb[Y1] = $y[$_] if !defined $bb[Y1] || $y[$_] < $bb[Y1];
+        $bb[Y2] = $y[$_] if !defined $bb[Y2] || $y[$_] > $bb[Y2];
     }
     
-    return ($x[0], $y[0], $x[-1], $y[-1]);
+    return @bb[X1,Y1,X2,Y2];
 }
 
 sub bounding_box_center {
diff --git a/lib/Slic3r/Polygon.pm b/lib/Slic3r/Polygon.pm
index 7241491bf..ae1a8cefd 100644
--- a/lib/Slic3r/Polygon.pm
+++ b/lib/Slic3r/Polygon.pm
@@ -68,28 +68,6 @@ sub subdivide {
     }
 }
 
-# returns false if the polygon is too tight to be printed
-sub is_printable {
-    my $self = shift;
-    my ($width) = @_;
-    
-    # try to get an inwards offset
-    # for a distance equal to half of the extrusion width;
-    # if no offset is possible, then polyline is not printable.
-    # we use flow_width here because this has to be consistent 
-    # with the thin wall detection in Layer->make_surfaces, 
-    # otherwise we could lose surfaces as that logic wouldn't
-    # detect them and we would be discarding them.
-    my $p = $self->clone;
-    $p->make_counter_clockwise;
-    return @{Slic3r::Geometry::Clipper::offset([$p], -$width / 2)} ? 1 : 0;
-}
-
-sub is_valid {
-    my $self = shift;
-    return @$self >= 3;
-}
-
 # for cw polygons this will return convex points!
 sub concave_points {
     my $self = shift;
diff --git a/lib/Slic3r/Print.pm b/lib/Slic3r/Print.pm
index 0eb04092a..455544275 100644
--- a/lib/Slic3r/Print.pm
+++ b/lib/Slic3r/Print.pm
@@ -302,7 +302,7 @@ sub bounding_box {
                 [ $copy->[X] + $object->size->[X], $copy->[Y] + $object->size->[Y] ];
         }
     }
-    return Slic3r::Geometry::BoundingBox->new_from_points(\@points);
+    return Slic3r::Geometry::BoundingBox->new_from_points([ map Slic3r::Point->new(@$_), @points ]);
 }
 
 sub size {
diff --git a/lib/Slic3r/Print/Object.pm b/lib/Slic3r/Print/Object.pm
index b5c0d2eec..bfbf0d420 100644
--- a/lib/Slic3r/Print/Object.pm
+++ b/lib/Slic3r/Print/Object.pm
@@ -3,7 +3,7 @@ use Moo;
 
 use List::Util qw(min max sum first);
 use Slic3r::ExtrusionPath ':roles';
-use Slic3r::Geometry qw(Z PI scale unscale deg2rad rad2deg scaled_epsilon chained_path_points);
+use Slic3r::Geometry qw(X Y Z PI scale unscale deg2rad rad2deg scaled_epsilon chained_path_points);
 use Slic3r::Geometry::Clipper qw(diff diff_ex intersection intersection_ex union union_ex 
     offset offset_ex offset2);
 use Slic3r::Surface ':types';
@@ -128,7 +128,7 @@ sub bounding_box {
     my $self = shift;
     
     # since the object is aligned to origin, bounding box coincides with size
-    return Slic3r::Geometry::BoundingBox->new_from_points([ [0,0], $self->size ]);
+    return Slic3r::Geometry::BoundingBox->new_from_points([ map Slic3r::Point->new(@$_[X,Y]), [0,0], $self->size ]);
 }
 
 sub slice {
diff --git a/xs/src/ExPolygon.cpp b/xs/src/ExPolygon.cpp
index 33d71b497..ce1ad307d 100644
--- a/xs/src/ExPolygon.cpp
+++ b/xs/src/ExPolygon.cpp
@@ -40,6 +40,16 @@ ExPolygon::area() const
     return a;
 }
 
+bool
+ExPolygon::is_valid() const
+{
+    if (!this->contour.is_valid() || !this->contour.is_counter_clockwise()) return false;
+    for (Polygons::const_iterator it = this->holes.begin(); it != this->holes.end(); ++it) {
+        if (!(*it).is_valid() || (*it).is_counter_clockwise()) return false;
+    }
+    return true;
+}
+
 SV*
 ExPolygon::to_SV() {
     const unsigned int num_holes = this->holes.size();
diff --git a/xs/src/ExPolygon.hpp b/xs/src/ExPolygon.hpp
index 62f919ead..fa4cbbe20 100644
--- a/xs/src/ExPolygon.hpp
+++ b/xs/src/ExPolygon.hpp
@@ -20,6 +20,7 @@ class ExPolygon
     void translate(double x, double y);
     void rotate(double angle, Point* center);
     double area() const;
+    bool is_valid() const;
 };
 
 typedef std::vector<ExPolygon> ExPolygons;
diff --git a/xs/src/Polygon.cpp b/xs/src/Polygon.cpp
index fc3f54f57..78b4b63b3 100644
--- a/xs/src/Polygon.cpp
+++ b/xs/src/Polygon.cpp
@@ -92,4 +92,10 @@ Polygon::make_clockwise()
     return false;
 }
 
+bool
+Polygon::is_valid() const
+{
+    return this->points.size() >= 3;
+}
+
 }
diff --git a/xs/src/Polygon.hpp b/xs/src/Polygon.hpp
index dcab04059..da913df19 100644
--- a/xs/src/Polygon.hpp
+++ b/xs/src/Polygon.hpp
@@ -20,6 +20,7 @@ class Polygon : public MultiPoint {
     bool is_counter_clockwise() const;
     bool make_counter_clockwise();
     bool make_clockwise();
+    bool is_valid() const;
 };
 
 typedef std::vector<Polygon> Polygons;
diff --git a/xs/t/04_expolygon.t b/xs/t/04_expolygon.t
index 8e14e589c..15f6924cf 100644
--- a/xs/t/04_expolygon.t
+++ b/xs/t/04_expolygon.t
@@ -4,7 +4,7 @@ use strict;
 use warnings;
 
 use Slic3r::XS;
-use Test::More tests => 20;
+use Test::More tests => 21;
 
 use constant PI => 4 * atan2(1, 1);
 
@@ -23,6 +23,7 @@ my $hole_in_square = [  # cw
 
 my $expolygon = Slic3r::ExPolygon->new($square, $hole_in_square);
 
+ok $expolygon->is_valid, 'is_valid';
 is ref($expolygon->pp), 'ARRAY', 'expolygon pp is unblessed';
 is_deeply $expolygon->pp, [$square, $hole_in_square], 'expolygon roundtrip';
 
diff --git a/xs/t/06_polygon.t b/xs/t/06_polygon.t
index cf81c5e46..5bbdcb4a2 100644
--- a/xs/t/06_polygon.t
+++ b/xs/t/06_polygon.t
@@ -4,7 +4,7 @@ use strict;
 use warnings;
 
 use Slic3r::XS;
-use Test::More tests => 12;
+use Test::More tests => 13;
 
 my $square = [  # ccw
     [100, 100],
@@ -14,6 +14,7 @@ my $square = [  # ccw
 ];
 
 my $polygon = Slic3r::Polygon->new(@$square);
+ok $polygon->is_valid, 'is_valid';
 is_deeply $polygon->pp, $square, 'polygon roundtrip';
 
 is ref($polygon->arrayref), 'ARRAY', 'polygon arrayref is unblessed';
diff --git a/xs/xsp/ExPolygon.xsp b/xs/xsp/ExPolygon.xsp
index ed64ba8c1..e4eabe943 100644
--- a/xs/xsp/ExPolygon.xsp
+++ b/xs/xsp/ExPolygon.xsp
@@ -20,6 +20,7 @@
     void scale(double factor);
     void translate(double x, double y);
     double area();
+    bool is_valid();
 %{
 
 ExPolygon*
diff --git a/xs/xsp/Polygon.xsp b/xs/xsp/Polygon.xsp
index 7b8578d8b..78a1e2edc 100644
--- a/xs/xsp/Polygon.xsp
+++ b/xs/xsp/Polygon.xsp
@@ -27,6 +27,7 @@
     bool is_counter_clockwise();
     bool make_counter_clockwise();
     bool make_clockwise();
+    bool is_valid();
 %{
 
 Polygon*