diff --git a/lib/Slic3r/Layer.pm b/lib/Slic3r/Layer.pm
index 9c975ca31..a715a971e 100644
--- a/lib/Slic3r/Layer.pm
+++ b/lib/Slic3r/Layer.pm
@@ -104,7 +104,6 @@ sub add_line {
     my $self = shift;
     my ($line) = @_;
     
-    $line = Slic3r::Line->cast($line);
     return if $line->a->coincides_with($line->b);
     
     push @{ $self->lines }, $line;
@@ -135,7 +134,7 @@ sub make_surfaces {
     # so a simple head-to-tail algorithm would work
     
     my @lines = ();
-    push @lines, map $_->p, @{$self->lines};
+    push @lines, @{$self->lines};
     #@lines = grep line_length($_) > xx, @lines;
     
     #use Slic3r::SVG;
diff --git a/lib/Slic3r/Line.pm b/lib/Slic3r/Line.pm
index b4ab97b6b..a22d2eb80 100644
--- a/lib/Slic3r/Line.pm
+++ b/lib/Slic3r/Line.pm
@@ -1,26 +1,25 @@
 package Slic3r::Line;
-use Moo;
+use strict;
+use warnings;
 
-# arrayref of points
-has 'points' => (
-    is          => 'rw',
-    default     => sub { [] },
-    required    => 1,
-);
-
-sub cast {
+sub new {
     my $class = shift;
-    my ($line, %args) = @_;
-    if (ref $line eq 'ARRAY') {
-        @$line == 2 or die "Line needs two points!";
-        return $class->new(points => [ map Slic3r::Point->new($_), @$line ], %args);
+    my $self;
+    if (@_ == 2) {
+        $self = [ map Slic3r::Point->new($_), @_ ];
+    } elsif (ref $_[0] eq 'ARRAY') {
+        $self = [ map Slic3r::Point->new($_), @{$_[0]} ];
+    } elsif ($_[0]->isa(__PACKAGE__)) {
+        return $_[0];
     } else {
-        return $line;
+        die "Invalid argument for $class->new";
     }
+    bless $self, $class;
+    return $self;
 }
 
-sub a { return $_[0]->points->[0] }
-sub b { return $_[0]->points->[1] }
+sub a { $_[0][0] }
+sub b { $_[0][1] }
 
 sub id {
     my $self = shift;
@@ -29,7 +28,7 @@ sub id {
 
 sub ordered_id {
     my $self = shift;
-    return join('-', sort map $_->id, @{$self->points});
+    return join('-', sort map $_->id, @$self);
 }
 
 sub coordinates {
@@ -37,11 +36,6 @@ sub coordinates {
     return ($self->a->coordinates, $self->b->coordinates);
 }
 
-sub p {
-    my $self = shift;
-    return [ $self->a, $self->b ];
-}
-
 sub coincides_with {
     my $self = shift;
     my ($line) = @_;
@@ -60,17 +54,15 @@ sub has_segment {
     my $self = shift;
     my ($line) = @_;
     
-    $line = $line->p if $line->isa('Slic3r::Line');
-    
     # a segment belongs to another segment if its points belong to it
-    return Slic3r::Geometry::point_in_segment($line->[0], $self->p)
-        && Slic3r::Geometry::point_in_segment($line->[1], $self->p);
+    return Slic3r::Geometry::point_in_segment($line->[0], $self)
+        && Slic3r::Geometry::point_in_segment($line->[1], $self);
 }
 
 sub parallel_to {
     my $self = shift;
     my ($line) = @_;
-    return Slic3r::Geometry::lines_parallel($self->p, $line->p);
+    return Slic3r::Geometry::lines_parallel($self, $line);
 }
 
 1;
diff --git a/lib/Slic3r/Line/FacetEdge.pm b/lib/Slic3r/Line/FacetEdge.pm
index d229c7ca4..411b1b14a 100644
--- a/lib/Slic3r/Line/FacetEdge.pm
+++ b/lib/Slic3r/Line/FacetEdge.pm
@@ -3,6 +3,7 @@ use Moo;
 
 extends 'Slic3r::Line';
 
-has 'edge_type' => (is => 'ro');  # top/bottom
+use Slic3r::Line::FacetEdge::Bottom;
+use Slic3r::Line::FacetEdge::Top;
 
 1;
diff --git a/lib/Slic3r/Line/FacetEdge/Bottom.pm b/lib/Slic3r/Line/FacetEdge/Bottom.pm
new file mode 100644
index 000000000..9efc84da7
--- /dev/null
+++ b/lib/Slic3r/Line/FacetEdge/Bottom.pm
@@ -0,0 +1,6 @@
+package Slic3r::Line::FacetEdge::Bottom;
+use Moo;
+
+extends 'Slic3r::Line::FacetEdge';
+
+1;
diff --git a/lib/Slic3r/Line/FacetEdge/Top.pm b/lib/Slic3r/Line/FacetEdge/Top.pm
new file mode 100644
index 000000000..c08599eb7
--- /dev/null
+++ b/lib/Slic3r/Line/FacetEdge/Top.pm
@@ -0,0 +1,6 @@
+package Slic3r::Line::FacetEdge::Top;
+use Moo;
+
+extends 'Slic3r::Line::FacetEdge';
+
+1;
diff --git a/lib/Slic3r/Point.pm b/lib/Slic3r/Point.pm
index a79093b07..5ddb4f495 100644
--- a/lib/Slic3r/Point.pm
+++ b/lib/Slic3r/Point.pm
@@ -12,6 +12,8 @@ sub new {
     } elsif ($_[0]->isa(__PACKAGE__)) {
         return $_[0];
     } else {
+        use XXX;
+        ZZZ "test";
         die "Invalid arguments for ${class}->new";
     }
     bless $self, $class;
diff --git a/lib/Slic3r/Polyline.pm b/lib/Slic3r/Polyline.pm
index 40e7e032c..5d8e46f27 100644
--- a/lib/Slic3r/Polyline.pm
+++ b/lib/Slic3r/Polyline.pm
@@ -34,7 +34,7 @@ sub lines {
     my $previous_point;
     foreach my $point (@{ $self->points }) {
         if ($previous_point) {
-            push @lines, Slic3r::Line->new(points => [ $previous_point, $point ]);
+            push @lines, Slic3r::Line->new($previous_point, $point);
         }
         $previous_point = $point;
     }
diff --git a/lib/Slic3r/Polyline/Closed.pm b/lib/Slic3r/Polyline/Closed.pm
index ee62523fd..dd9a742f3 100644
--- a/lib/Slic3r/Polyline/Closed.pm
+++ b/lib/Slic3r/Polyline/Closed.pm
@@ -11,7 +11,7 @@ sub lines {
     
     # since this is a closed polyline, we just add a line at the end,
     # connecting the last and the first point
-    push @lines, Slic3r::Line->new(points => [$self->points->[-1], $self->points->[0]]);
+    push @lines, Slic3r::Line->new($self->points->[-1], $self->points->[0]);
     return @lines;
 }
 
diff --git a/lib/Slic3r/STL.pm b/lib/Slic3r/STL.pm
index f06362733..bd6834e57 100644
--- a/lib/Slic3r/STL.pm
+++ b/lib/Slic3r/STL.pm
@@ -150,11 +150,10 @@ sub intersect_facet {
         
         if ($a->[Z] == $b->[Z] && $a->[Z] == $z) {
             # edge is horizontal and belongs to the current layer
-            my $edge_type = (grep $_->[Z] > $z, @$vertices) ? 'bottom' : 'top';
-            ($a, $b) = ($b, $a) if $edge_type eq 'bottom';
-            push @lines, Slic3r::Line::FacetEdge->cast(
-                [ [$a->[X], $a->[Y]], [$b->[X], $b->[Y]] ],
-                edge_type => $edge_type,
+            my $edge_type = (grep $_->[Z] > $z, @$vertices) ? 'Bottom' : 'Top';
+            ($a, $b) = ($b, $a) if $edge_type eq 'Bottom';
+            push @lines, "Slic3r::Line::FacetEdge::$edge_type"->new(
+                [$a->[X], $a->[Y]], [$b->[X], $b->[Y]],
             );
             #print "Horizontal edge at $z!\n";
             
@@ -192,7 +191,7 @@ sub intersect_facet {
         #}
         
         # connect points:
-        push @lines, Slic3r::Line->cast([ @intersection_points ]);
+        push @lines, Slic3r::Line->new(@intersection_points);
         #printf "  intersection points = %f,%f - %f,%f\n", map @$_, @intersection_points;
     }
     
diff --git a/t/stl.t b/t/stl.t
index d6fc8e25f..51b38ca75 100644
--- a/t/stl.t
+++ b/t/stl.t
@@ -2,7 +2,7 @@ use Test::More;
 use strict;
 use warnings;
 
-plan tests => 11;
+plan tests => 9;
 
 BEGIN {
     use FindBin;
@@ -32,15 +32,13 @@ is_deeply lines(24, 10, 20), [ [ [4, 4],     [1, 9]     ] ], 'one vertex on plan
 
 my @lower = $stl->intersect_facet(vertices(22, 20, 20), $z);
 my @upper = $stl->intersect_facet(vertices(20, 20, 10), $z);
-isa_ok $lower[0], 'Slic3r::Line::FacetEdge', 'bottom edge on layer';
-isa_ok $upper[0], 'Slic3r::Line::FacetEdge', 'upper edge on layer';
-is $lower[0]->edge_type, 'bottom', 'lower edge is detected as bottom';
-is $upper[0]->edge_type, 'top', 'upper edge is detected as top';
+isa_ok $lower[0], 'Slic3r::Line::FacetEdge::Bottom', 'bottom edge on layer';
+isa_ok $upper[0], 'Slic3r::Line::FacetEdge::Top', 'upper edge on layer';
 
 sub vertices {
     [ map [ @{$points[$_]}, $_[$_] ], 0..2 ]
 }
 
 sub lines {
-    [ map [ map ref $_ eq 'Slic3r::Point' ? $_->p : [ map sprintf('%.0f', $_), @$_ ], @$_ ], map $_->p, $stl->intersect_facet(vertices(@_), $z) ];
+    [ map [ map [ map sprintf('%.0f', $_), @$_ ], @$_ ], $stl->intersect_facet(vertices(@_), $z) ];
 }