diff --git a/app-proto/sketch-outline/src/assembly.rs b/app-proto/sketch-outline/src/assembly.rs
index 4cd769c..a4c9a0f 100644
--- a/app-proto/sketch-outline/src/assembly.rs
+++ b/app-proto/sketch-outline/src/assembly.rs
@@ -1,7 +1,7 @@
 use nalgebra::DVector;
 use rustc_hash::FxHashSet;
 use slab::Slab;
-use sycamore::reactive::Signal;
+use sycamore::prelude::*;
 
 #[derive(Clone, PartialEq)]
 pub struct Element {
@@ -22,4 +22,22 @@ pub struct Constraint {
 pub struct Assembly {
     pub elements: Signal<Slab<Element>>,
     pub constraints: Signal<Slab<Constraint>>
+}
+
+impl Assembly {
+    pub fn new() -> Assembly {
+        Assembly {
+            elements: create_signal(Slab::new()),
+            constraints: create_signal(Slab::new())
+        }
+    }
+    
+    pub fn insert_constraint(&self, constraint: Constraint) {
+        let args = constraint.args;
+        let key = self.constraints.update(|csts| csts.insert(constraint));
+        self.elements.update(|elts| {
+            elts[args.0].constraints.insert(key);
+            elts[args.1].constraints.insert(key);
+        })
+    }
 }
\ No newline at end of file
diff --git a/app-proto/sketch-outline/src/main.rs b/app-proto/sketch-outline/src/main.rs
index 20ae651..b86f979 100644
--- a/app-proto/sketch-outline/src/main.rs
+++ b/app-proto/sketch-outline/src/main.rs
@@ -7,7 +7,7 @@ use rustc_hash::FxHashSet;
 use slab::Slab;
 use sycamore::prelude::*;
 
-use assembly::{Assembly, Element};
+use assembly::{Assembly, Constraint, Element};
 use display::Display;
 use outline::Outline;
 
@@ -17,32 +17,30 @@ struct AppState {
     selection: Signal<FxHashSet<usize>>
 }
 
+impl AppState {
+    fn new() -> AppState {
+        AppState {
+            assembly: Assembly::new(),
+            selection: create_signal(FxHashSet::default())
+        }
+    }
+}
+
 fn main() {
     sycamore::render(|| {
-        let state = AppState {
-            assembly: Assembly {
-                elements: create_signal(Slab::new()),
-                constraints: create_signal(Slab::new())
-            },
-            selection: create_signal(FxHashSet::default())
-        };
-        state.assembly.elements.update(
+        let state = AppState::new();
+        let key_a = state.assembly.elements.update(
             |elts| elts.insert(
                 Element {
                     id: String::from("wing_a"),
                     label: String::from("Wing A"),
                     color: [1.00_f32, 0.25_f32, 0.00_f32],
                     rep: DVector::<f64>::from_column_slice(&[0.5, 0.5, 0.0, 0.5, -0.25]),
-                    constraints: {
-                        let mut set = FxHashSet::default();
-                        set.insert(1);
-                        set.insert(2);
-                        set
-                    }
+                    constraints: FxHashSet::default()
                 }
             )
         );
-        state.assembly.elements.update(
+        let key_b = state.assembly.elements.update(
             |elts| elts.insert(
                 Element {
                     id: String::from("wing_b"),
@@ -64,6 +62,10 @@ fn main() {
                 }
             )
         );
+        state.assembly.insert_constraint(Constraint {
+            args: (key_a, key_b),
+            rep: 0.5
+        });
         provide_context(state);
         
         view! {