diff --git a/src/layout.rs b/src/layout.rs
index 6aacf83..7755a9b 100644
--- a/src/layout.rs
+++ b/src/layout.rs
@@ -22,14 +22,14 @@ use crate::connectivity::{
 use crate::graph::{GenericIndex, GetNodeIndex};
 use crate::guide::Guide;
 use crate::layout::bend::BendIndex;
-use crate::layout::geometry::{BendWeight, DotWeight, Geometry, SegWeight};
+use crate::layout::dot::DotWeight;
+use crate::layout::geometry::{BendWeightTrait, DotWeightTrait, Geometry, SegWeightTrait};
 use crate::layout::seg::{SegIndex, SeqLooseSegWeight};
 use crate::layout::{
     bend::{FixedBendIndex, LooseBendIndex, LooseBendWeight},
     dot::{DotIndex, FixedDotIndex, FixedDotWeight, LooseDotIndex, LooseDotWeight},
     geometry::{
-        GeometryGraph, GeometryIndex, GeometryLabel, GeometryWeight, GetComponentIndex,
-        MakePrimitive, Retag,
+        GeometryIndex, GeometryLabel, GeometryWeight, GetComponentIndex, MakePrimitive, Retag,
     },
     seg::{FixedSegIndex, FixedSegWeight, LoneLooseSegIndex, LoneLooseSegWeight, SeqLooseSegIndex},
 };
@@ -75,7 +75,7 @@ pub struct AlreadyConnected(pub i64, pub GeometryIndex);
 pub struct Layout {
     rtree: RTree<RTreeWrapper>,
     connectivity: ConnectivityGraph,
-    geometry: Geometry<DotIndex, SegIndex, BendIndex>,
+    geometry: Geometry<GeometryWeight, DotWeight, DotIndex, SegIndex, BendIndex>,
 }
 
 #[debug_invariant(self.geometry.graph().node_count() == self.rtree.size())]
@@ -224,7 +224,7 @@ impl Layout {
 
     #[debug_ensures(ret.is_ok() -> self.geometry.graph().node_count() == old(self.geometry.graph().node_count() + 1))]
     #[debug_ensures(ret.is_err() -> self.geometry.graph().node_count() == old(self.geometry.graph().node_count()))]
-    fn add_dot_infringably<W: DotWeight>(
+    fn add_dot_infringably<W: DotWeightTrait<GeometryWeight>>(
         &mut self,
         weight: W,
         infringables: &[GeometryIndex],
@@ -604,7 +604,7 @@ impl Layout {
     #[debug_ensures(ret.is_ok() -> self.geometry.graph().edge_count() == old(self.geometry.graph().edge_count() + 2))]
     #[debug_ensures(ret.is_err() -> self.geometry.graph().node_count() == old(self.geometry.graph().node_count()))]
     #[debug_ensures(ret.is_err() -> self.geometry.graph().edge_count() == old(self.geometry.graph().edge_count()))]
-    fn add_seg_infringably<W: SegWeight>(
+    fn add_seg_infringably<W: SegWeightTrait<GeometryWeight>>(
         &mut self,
         from: DotIndex,
         to: DotIndex,
@@ -681,7 +681,7 @@ impl Layout {
     #[debug_ensures(ret.is_err() -> self.geometry.graph().node_count() == old(self.geometry.graph().node_count()))]
     #[debug_ensures(ret.is_ok() -> self.geometry.graph().edge_count() == old(self.geometry.graph().edge_count() + 3))]
     #[debug_ensures(ret.is_err() -> self.geometry.graph().edge_count() == old(self.geometry.graph().edge_count()))]
-    fn add_core_bend_infringably<W: BendWeight>(
+    fn add_core_bend_infringably<W: BendWeightTrait<GeometryWeight>>(
         &mut self,
         from: DotIndex,
         to: DotIndex,
@@ -703,7 +703,7 @@ impl Layout {
     #[debug_ensures(ret.is_err() -> self.geometry.graph().node_count() == old(self.geometry.graph().node_count()))]
     #[debug_ensures(ret.is_ok() -> self.geometry.graph().edge_count() == old(self.geometry.graph().edge_count() + 4))]
     #[debug_ensures(ret.is_err() -> self.geometry.graph().edge_count() == old(self.geometry.graph().edge_count()))]
-    fn add_outer_bend_infringably<W: BendWeight>(
+    fn add_outer_bend_infringably<W: BendWeightTrait<GeometryWeight>>(
         &mut self,
         from: LooseDotIndex,
         to: LooseDotIndex,
@@ -953,7 +953,7 @@ impl Layout {
 
     #[debug_ensures(self.geometry.graph().node_count() == old(self.geometry.graph().node_count()))]
     #[debug_ensures(self.geometry.graph().edge_count() == old(self.geometry.graph().edge_count()))]
-    pub fn geometry(&self) -> &Geometry<DotIndex, SegIndex, BendIndex> {
+    pub fn geometry(&self) -> &Geometry<GeometryWeight, DotWeight, DotIndex, SegIndex, BendIndex> {
         &self.geometry
     }
 
diff --git a/src/layout/bend.rs b/src/layout/bend.rs
index 26ac986..27ae154 100644
--- a/src/layout/bend.rs
+++ b/src/layout/bend.rs
@@ -8,7 +8,7 @@ use crate::{
 };
 
 use super::geometry::{
-    BendWeight, GeometryIndex, GeometryWeight, GetBandIndex, GetComponentIndex,
+    BendWeightTrait, GeometryIndex, GeometryWeight, GetBandIndex, GetComponentIndex,
     GetComponentIndexMut, GetOffset, GetWidth, MakePrimitive, Retag,
 };
 use petgraph::stable_graph::NodeIndex;
@@ -37,7 +37,7 @@ pub struct FixedBendWeight {
 }
 
 impl_fixed_weight!(FixedBendWeight, FixedBend, FixedBendIndex);
-impl BendWeight for FixedBendWeight {}
+impl BendWeightTrait<GeometryWeight> for FixedBendWeight {}
 
 impl GetWidth for FixedBendWeight {
     fn width(&self) -> f64 {
@@ -59,4 +59,4 @@ impl GetOffset for LooseBendWeight {
 }
 
 impl_loose_weight!(LooseBendWeight, LooseBend, LooseBendIndex);
-impl BendWeight for LooseBendWeight {}
+impl BendWeightTrait<GeometryWeight> for LooseBendWeight {}
diff --git a/src/layout/dot.rs b/src/layout/dot.rs
index 4841198..062fd39 100644
--- a/src/layout/dot.rs
+++ b/src/layout/dot.rs
@@ -9,7 +9,7 @@ use crate::{
 };
 
 use super::geometry::{
-    DotWeight, GeometryIndex, GeometryWeight, GetBandIndex, GetComponentIndex,
+    DotWeightTrait, GeometryIndex, GeometryWeight, GetBandIndex, GetComponentIndex,
     GetComponentIndexMut, GetWidth, MakePrimitive, Retag,
 };
 use petgraph::stable_graph::NodeIndex;
@@ -24,12 +24,42 @@ pub enum DotIndex {
 impl From<DotIndex> for GeometryIndex {
     fn from(dot: DotIndex) -> Self {
         match dot {
-            DotIndex::Fixed(fixed) => GeometryIndex::FixedDot(fixed),
-            DotIndex::Loose(loose) => GeometryIndex::LooseDot(loose),
+            DotIndex::Fixed(index) => GeometryIndex::FixedDot(index),
+            DotIndex::Loose(index) => GeometryIndex::LooseDot(index),
         }
     }
 }
 
+#[enum_dispatch(GetWidth)]
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub enum DotWeight {
+    Fixed(FixedDotWeight),
+    Loose(LooseDotWeight),
+}
+
+impl From<DotWeight> for GeometryWeight {
+    fn from(dot: DotWeight) -> Self {
+        match dot {
+            DotWeight::Fixed(weight) => GeometryWeight::FixedDot(weight),
+            DotWeight::Loose(weight) => GeometryWeight::LooseDot(weight),
+        }
+    }
+}
+
+impl TryFrom<GeometryWeight> for DotWeight {
+    type Error = (); // TODO.
+
+    fn try_from(weight: GeometryWeight) -> Result<DotWeight, ()> {
+        match weight {
+            GeometryWeight::FixedDot(weight) => Ok(DotWeight::Fixed(weight)),
+            GeometryWeight::LooseDot(weight) => Ok(DotWeight::Loose(weight)),
+            _ => unreachable!(),
+        }
+    }
+}
+
+impl DotWeightTrait<GeometryWeight> for DotWeight {}
+
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub struct FixedDotWeight {
     pub component: ComponentIndex,
@@ -37,7 +67,7 @@ pub struct FixedDotWeight {
 }
 
 impl_fixed_weight!(FixedDotWeight, FixedDot, FixedDotIndex);
-impl DotWeight for FixedDotWeight {}
+impl DotWeightTrait<GeometryWeight> for FixedDotWeight {}
 
 impl GetWidth for FixedDotWeight {
     fn width(&self) -> f64 {
@@ -52,7 +82,7 @@ pub struct LooseDotWeight {
 }
 
 impl_loose_weight!(LooseDotWeight, LooseDot, LooseDotIndex);
-impl DotWeight for LooseDotWeight {}
+impl DotWeightTrait<GeometryWeight> for LooseDotWeight {}
 
 impl GetWidth for LooseDotWeight {
     fn width(&self) -> f64 {
diff --git a/src/layout/geometry.rs b/src/layout/geometry.rs
index 8d8b588..bb3d435 100644
--- a/src/layout/geometry.rs
+++ b/src/layout/geometry.rs
@@ -44,6 +44,7 @@ pub trait GetWidth {
     fn width(&self) -> f64;
 }
 
+#[enum_dispatch]
 pub trait GetOffset {
     fn offset(&self) -> f64;
 }
@@ -96,8 +97,6 @@ macro_rules! impl_loose_weight {
     };
 }
 
-pub type GeometryGraph = StableDiGraph<GeometryWeight, GeometryLabel, usize>;
-
 #[enum_dispatch(Retag)]
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub enum GeometryWeight {
@@ -134,33 +133,55 @@ pub trait MakePrimitive {
     fn primitive<'a>(&self, layout: &'a Layout) -> Primitive<'a>;
 }
 
-pub trait DotWeight: GetWidth + Into<GeometryWeight> + Copy {}
-pub trait SegWeight: Into<GeometryWeight> + Copy {}
-pub trait BendWeight: Into<GeometryWeight> + Copy {}
+pub trait DotWeightTrait<GW>: GetWidth + Into<GW> + Copy {}
+pub trait SegWeightTrait<GW>: Into<GW> + Copy {}
+pub trait BendWeightTrait<GW>: Into<GW> + Copy {}
 
 #[derive(Debug)]
-pub struct Geometry<DI: GetNodeIndex, SI: GetNodeIndex, BI: GetNodeIndex> {
-    pub graph: GeometryGraph,
+pub struct Geometry<
+    GW: TryInto<DW>,
+    DW: DotWeightTrait<GW>,
+    DI: GetNodeIndex,
+    SI: GetNodeIndex,
+    BI: GetNodeIndex,
+> {
+    pub graph: StableDiGraph<GW, GeometryLabel, usize>,
+    weight_marker: PhantomData<GW>,
+    dot_weight_marker: PhantomData<DW>,
     dot_index_marker: PhantomData<DI>,
     seg_index_marker: PhantomData<SI>,
     bend_index_marker: PhantomData<BI>,
 }
 
-impl<DI: GetNodeIndex, SI: GetNodeIndex, BI: GetNodeIndex> Geometry<DI, SI, BI> {
+impl<
+        GW: TryInto<DW>,
+        DW: DotWeightTrait<GW> + Copy,
+        DI: GetNodeIndex,
+        SI: GetNodeIndex,
+        BI: GetNodeIndex,
+    > Geometry<GW, DW, DI, SI, BI>
+{
     pub fn new() -> Self {
         Self {
             graph: StableDiGraph::default(),
+            weight_marker: PhantomData,
+            dot_weight_marker: PhantomData,
             dot_index_marker: PhantomData,
             seg_index_marker: PhantomData,
             bend_index_marker: PhantomData,
         }
     }
 
-    pub fn add_dot<W: DotWeight>(&mut self, weight: W) -> GenericIndex<W> {
+    pub fn add_dot<W: DotWeightTrait<GW>>(&mut self, weight: W) -> GenericIndex<W> {
         GenericIndex::<W>::new(self.graph.add_node(weight.into()))
     }
 
-    pub fn add_seg<W: SegWeight>(&mut self, from: DI, to: DI, weight: W) -> GenericIndex<W> {
+    pub fn add_seg<W: SegWeightTrait<GW>>(
+        &mut self,
+        from: DI,
+        to: DI,
+        weight: W,
+    ) -> GenericIndex<W> {
         let seg = GenericIndex::<W>::new(self.graph.add_node(weight.into()));
 
         self.graph
@@ -171,7 +192,7 @@ impl<DI: GetNodeIndex, SI: GetNodeIndex, BI: GetNodeIndex> Geometry<DI, SI, BI>
         seg
     }
 
-    pub fn add_bend<W: BendWeight>(
+    pub fn add_bend<W: BendWeightTrait<GW>>(
         &mut self,
         from: DI,
         to: DI,
@@ -193,7 +214,7 @@ impl<DI: GetNodeIndex, SI: GetNodeIndex, BI: GetNodeIndex> Geometry<DI, SI, BI>
         bend
     }
 
-    pub fn graph(&self) -> &GeometryGraph {
+    pub fn graph(&self) -> &StableDiGraph<GW, GeometryLabel, usize> {
         &self.graph
     }
 }
diff --git a/src/layout/seg.rs b/src/layout/seg.rs
index dd14d22..8b371b0 100644
--- a/src/layout/seg.rs
+++ b/src/layout/seg.rs
@@ -9,7 +9,7 @@ use crate::{
 
 use super::geometry::{
     GeometryIndex, GeometryWeight, GetBandIndex, GetComponentIndex, GetComponentIndexMut, GetWidth,
-    MakePrimitive, Retag, SegWeight,
+    MakePrimitive, Retag, SegWeightTrait,
 };
 use petgraph::stable_graph::NodeIndex;
 
@@ -38,7 +38,7 @@ pub struct FixedSegWeight {
 }
 
 impl_fixed_weight!(FixedSegWeight, FixedSeg, FixedSegIndex);
-impl SegWeight for FixedSegWeight {}
+impl SegWeightTrait<GeometryWeight> for FixedSegWeight {}
 
 impl GetWidth for FixedSegWeight {
     fn width(&self) -> f64 {
@@ -52,7 +52,7 @@ pub struct LoneLooseSegWeight {
 }
 
 impl_loose_weight!(LoneLooseSegWeight, LoneLooseSeg, LoneLooseSegIndex);
-impl SegWeight for LoneLooseSegWeight {}
+impl SegWeightTrait<GeometryWeight> for LoneLooseSegWeight {}
 
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub struct SeqLooseSegWeight {
@@ -60,4 +60,4 @@ pub struct SeqLooseSegWeight {
 }
 
 impl_loose_weight!(SeqLooseSegWeight, SeqLooseSeg, SeqLooseSegIndex);
-impl SegWeight for SeqLooseSegWeight {}
+impl SegWeightTrait<GeometryWeight> for SeqLooseSegWeight {}