diff --git a/src/guide.rs b/src/guide.rs
index c8d524a..ddd0641 100644
--- a/src/guide.rs
+++ b/src/guide.rs
@@ -5,6 +5,7 @@ use crate::{
     graph::{BendIndex, DotIndex},
     layout::Layout,
     math::{self, Circle},
+    primitive::MakeShape,
     rules::{Conditions, Rules},
 };
 
diff --git a/src/layout.rs b/src/layout.rs
index c1eaff2..f3e77fc 100644
--- a/src/layout.rs
+++ b/src/layout.rs
@@ -13,7 +13,7 @@ use crate::graph::{
     BendIndex, BendWeight, DotIndex, DotWeight, Index, Interior, Label, Retag, SegIndex, SegWeight,
     Tag, TaggedIndex, Weight,
 };
-use crate::primitive::Primitive;
+use crate::primitive::{MakeShape, Primitive};
 use crate::segbend::Segbend;
 use crate::shape::{Shape, ShapeTrait};
 
@@ -49,7 +49,7 @@ impl Layout {
     }
 
     #[debug_ensures(self.graph.node_count() == old(self.graph.node_count() - 1))]
-    pub fn remove<Weight: std::marker::Copy>(&mut self, index: Index<Weight>) {
+    pub fn remove<W: std::marker::Copy>(&mut self, index: Index<W>) {
         // Unnecessary retag. It should be possible to elide it.
         let weight = *self.graph.node_weight(index.index).unwrap();
 
@@ -236,11 +236,14 @@ impl Layout {
     #[debug_ensures(ret.is_ok() -> self.graph.node_count() == old(self.graph.node_count()))]
     #[debug_ensures(ret.is_ok() -> self.graph.edge_count() == old(self.graph.edge_count()))]
     #[debug_ensures(ret.is_err() -> self.graph.node_count() == old(self.graph.node_count() - 1))]
-    fn fail_and_remove_if_collides_except<Weight: std::marker::Copy>(
+    fn fail_and_remove_if_collides_except<W: std::marker::Copy>(
         &mut self,
-        index: Index<Weight>,
+        index: Index<W>,
         except: &[TaggedIndex],
-    ) -> Result<(), ()> {
+    ) -> Result<(), ()>
+    where
+        for<'a> Primitive<'a, W>: MakeShape,
+    {
         if let Some(..) = self.detect_collision_except(index, except) {
             self.remove(index);
             return Err(());
@@ -310,15 +313,18 @@ impl Layout {
         Ok(())
     }
 
-    pub fn primitive<Weight>(&self, index: Index<Weight>) -> Primitive<Weight> {
+    pub fn primitive<W>(&self, index: Index<W>) -> Primitive<W> {
         Primitive::new(index, &self.graph)
     }
 
-    fn detect_collision_except<Weight: std::marker::Copy>(
+    fn detect_collision_except<W>(
         &self,
-        index: Index<Weight>,
+        index: Index<W>,
         except: &[TaggedIndex],
-    ) -> Option<TaggedIndex> {
+    ) -> Option<TaggedIndex>
+    where
+        for<'a> Primitive<'a, W>: MakeShape,
+    {
         let primitive = self.primitive(index);
         let shape = primitive.shape();
 
diff --git a/src/mesh.rs b/src/mesh.rs
index 1244915..6325d94 100644
--- a/src/mesh.rs
+++ b/src/mesh.rs
@@ -7,8 +7,8 @@ use spade::{
     DelaunayTriangulation, HasPosition, InsertionError, Point2, Triangulation,
 };
 
-use crate::shape::ShapeTrait;
 use crate::{graph::DotIndex, layout::Layout};
+use crate::{primitive::MakeShape, shape::ShapeTrait};
 
 #[derive(Debug, Clone)]
 struct Vertex {
diff --git a/src/primitive.rs b/src/primitive.rs
index 8097f03..69383d8 100644
--- a/src/primitive.rs
+++ b/src/primitive.rs
@@ -1,5 +1,6 @@
 use std::mem::{self, swap};
 
+use enum_dispatch::enum_dispatch;
 use petgraph::stable_graph::{NodeIndex, StableDiGraph};
 use petgraph::Direction::{Incoming, Outgoing};
 
@@ -10,6 +11,10 @@ use crate::graph::{
 use crate::math::{self, Circle};
 use crate::shape::{BendShape, DotShape, SegShape, Shape, ShapeTrait};
 
+pub trait MakeShape {
+    fn shape(&self) -> Shape;
+}
+
 #[derive(Debug)]
 pub struct Primitive<'a, W> {
     pub index: Index<W>,
@@ -21,38 +26,6 @@ impl<'a, W> Primitive<'a, W> {
         Self { index, graph }
     }
 
-    pub fn shape(&self) -> Shape {
-        match self.tagged_weight() {
-            Weight::Dot(dot) => Shape::Dot(DotShape { c: dot.circle }),
-            Weight::Seg(seg) => {
-                let ends = self.ends();
-                Shape::Seg(SegShape {
-                    from: self.primitive(ends.0).weight().circle.pos,
-                    to: self.primitive(ends.1).weight().circle.pos,
-                    width: seg.width,
-                })
-            }
-            Weight::Bend(bend) => {
-                let ends = self.ends();
-
-                let mut bend_shape = BendShape {
-                    from: self.primitive(ends.0).weight().circle.pos,
-                    to: self.primitive(ends.1).weight().circle.pos,
-                    c: Circle {
-                        pos: self.primitive(self.core().unwrap()).weight().circle.pos,
-                        r: self.inner_radius(),
-                    },
-                    width: self.primitive(ends.0).weight().circle.r * 2.0,
-                };
-
-                if bend.cw {
-                    swap(&mut bend_shape.from, &mut bend_shape.to);
-                }
-                Shape::Bend(bend_shape)
-            }
-        }
-    }
-
     fn inner_radius(&self) -> f64 {
         let mut r = 0.0;
         let mut layer = BendIndex::new(self.index.index);
@@ -224,13 +197,13 @@ impl<'a, W> Primitive<'a, W> {
     }
 }
 
-impl<'a, Weight> Interior<TaggedIndex> for Primitive<'a, Weight> {
+impl<'a, W> Interior<TaggedIndex> for Primitive<'a, W> {
     fn interior(&self) -> Vec<TaggedIndex> {
         vec![self.tagged_index()]
     }
 }
 
-impl<'a, Weight> Ends<DotIndex, DotIndex> for Primitive<'a, Weight> {
+impl<'a, W> Ends<DotIndex, DotIndex> for Primitive<'a, W> {
     fn ends(&self) -> (DotIndex, DotIndex) {
         let v = self
             .graph
@@ -254,8 +227,6 @@ impl<'a, Weight> Ends<DotIndex, DotIndex> for Primitive<'a, Weight> {
 }
 
 pub type Dot<'a> = Primitive<'a, DotWeight>;
-pub type Seg<'a> = Primitive<'a, SegWeight>;
-pub type Bend<'a> = Primitive<'a, BendWeight>;
 
 impl<'a> Dot<'a> {
     pub fn bend(&self) -> Option<BendIndex> {
@@ -296,6 +267,16 @@ impl<'a> Dot<'a> {
     }
 }
 
+impl<'a> MakeShape for Dot<'a> {
+    fn shape(&self) -> Shape {
+        Shape::Dot(DotShape {
+            c: self.weight().circle,
+        })
+    }
+}
+
+pub type Seg<'a> = Primitive<'a, SegWeight>;
+
 impl<'a> Seg<'a> {
     pub fn next(&self) -> Option<DotIndex> {
         self.next_node().map(|ni| DotIndex::new(ni))
@@ -310,6 +291,19 @@ impl<'a> Seg<'a> {
     }
 }
 
+impl<'a> MakeShape for Seg<'a> {
+    fn shape(&self) -> Shape {
+        let ends = self.ends();
+        Shape::Seg(SegShape {
+            from: self.primitive(ends.0).weight().circle.pos,
+            to: self.primitive(ends.1).weight().circle.pos,
+            width: self.weight().width,
+        })
+    }
+}
+
+pub type Bend<'a> = Primitive<'a, BendWeight>;
+
 impl<'a> Bend<'a> {
     pub fn around(&self) -> TaggedIndex {
         if let Some(inner) = self.inner() {
@@ -365,3 +359,24 @@ impl<'a> Bend<'a> {
         math::cross_product(end1 - center, end2 - center)
     }
 }
+
+impl<'a> MakeShape for Bend<'a> {
+    fn shape(&self) -> Shape {
+        let ends = self.ends();
+
+        let mut bend_shape = BendShape {
+            from: self.primitive(ends.0).weight().circle.pos,
+            to: self.primitive(ends.1).weight().circle.pos,
+            c: Circle {
+                pos: self.primitive(self.core().unwrap()).weight().circle.pos,
+                r: self.inner_radius(),
+            },
+            width: self.primitive(ends.0).weight().circle.r * 2.0,
+        };
+
+        if self.weight().cw {
+            swap(&mut bend_shape.from, &mut bend_shape.to);
+        }
+        Shape::Bend(bend_shape)
+    }
+}
diff --git a/src/tracer.rs b/src/tracer.rs
index 429c6e7..ecc5004 100644
--- a/src/tracer.rs
+++ b/src/tracer.rs
@@ -6,6 +6,7 @@ use crate::{
     graph::{BendIndex, DotIndex, Ends},
     layout::Layout,
     mesh::{Mesh, MeshEdgeReference, VertexIndex},
+    primitive::MakeShape,
     rules::Rules,
 };