diff --git a/crates/fj-operations/src/difference_2d.rs b/crates/fj-operations/src/difference_2d.rs
index d4518dc61..7c6bb8638 100644
--- a/crates/fj-operations/src/difference_2d.rs
+++ b/crates/fj-operations/src/difference_2d.rs
@@ -18,7 +18,7 @@ impl Shape for fj::Difference2d {
 
     fn compute_brep(
         &self,
-        objects: &Objects,
+        objects: &mut Objects,
         debug_info: &mut DebugInfo,
     ) -> Result<Self::Brep, ValidationError> {
         // This method assumes that `b` is fully contained within `a`:
diff --git a/crates/fj-operations/src/group.rs b/crates/fj-operations/src/group.rs
index f34be965f..b675b5f8a 100644
--- a/crates/fj-operations/src/group.rs
+++ b/crates/fj-operations/src/group.rs
@@ -12,7 +12,7 @@ impl Shape for fj::Group {
 
     fn compute_brep(
         &self,
-        objects: &Objects,
+        objects: &mut Objects,
         debug_info: &mut DebugInfo,
     ) -> Result<Self::Brep, ValidationError> {
         let mut faces = FaceSet::new();
diff --git a/crates/fj-operations/src/lib.rs b/crates/fj-operations/src/lib.rs
index 1dc50ef78..50f5eb923 100644
--- a/crates/fj-operations/src/lib.rs
+++ b/crates/fj-operations/src/lib.rs
@@ -44,7 +44,7 @@ pub trait Shape {
     /// Compute the boundary representation of the shape
     fn compute_brep(
         &self,
-        objects: &Objects,
+        objects: &mut Objects,
         debug_info: &mut DebugInfo,
     ) -> Result<Self::Brep, ValidationError>;
 
@@ -60,7 +60,7 @@ impl Shape for fj::Shape {
 
     fn compute_brep(
         &self,
-        objects: &Objects,
+        objects: &mut Objects,
         debug_info: &mut DebugInfo,
     ) -> Result<Self::Brep, ValidationError> {
         match self {
@@ -96,7 +96,7 @@ impl Shape for fj::Shape2d {
 
     fn compute_brep(
         &self,
-        objects: &Objects,
+        objects: &mut Objects,
         debug_info: &mut DebugInfo,
     ) -> Result<Self::Brep, ValidationError> {
         match self {
diff --git a/crates/fj-operations/src/shape_processor.rs b/crates/fj-operations/src/shape_processor.rs
index 87c17fd21..21e32f1fb 100644
--- a/crates/fj-operations/src/shape_processor.rs
+++ b/crates/fj-operations/src/shape_processor.rs
@@ -42,9 +42,9 @@ impl ShapeProcessor {
             Some(user_defined_tolerance) => user_defined_tolerance,
         };
 
-        let objects = Objects::new();
+        let mut objects = Objects::new();
         let mut debug_info = DebugInfo::new();
-        let shape = shape.compute_brep(&objects, &mut debug_info)?;
+        let shape = shape.compute_brep(&mut objects, &mut debug_info)?;
         let mesh = (&shape, tolerance).triangulate();
 
         Ok(ProcessedShape {
diff --git a/crates/fj-operations/src/sketch.rs b/crates/fj-operations/src/sketch.rs
index 041fca4eb..2e41b3943 100644
--- a/crates/fj-operations/src/sketch.rs
+++ b/crates/fj-operations/src/sketch.rs
@@ -17,7 +17,7 @@ impl Shape for fj::Sketch {
 
     fn compute_brep(
         &self,
-        objects: &Objects,
+        objects: &mut Objects,
         _: &mut DebugInfo,
     ) -> Result<Self::Brep, ValidationError> {
         let surface = objects.surfaces.xy_plane();
diff --git a/crates/fj-operations/src/sweep.rs b/crates/fj-operations/src/sweep.rs
index b3d2dc35e..97025a3da 100644
--- a/crates/fj-operations/src/sweep.rs
+++ b/crates/fj-operations/src/sweep.rs
@@ -16,7 +16,7 @@ impl Shape for fj::Sweep {
 
     fn compute_brep(
         &self,
-        objects: &Objects,
+        objects: &mut Objects,
         debug_info: &mut DebugInfo,
     ) -> Result<Self::Brep, ValidationError> {
         let sketch = self.shape().compute_brep(objects, debug_info)?;
diff --git a/crates/fj-operations/src/transform.rs b/crates/fj-operations/src/transform.rs
index 5cde79679..f930b735f 100644
--- a/crates/fj-operations/src/transform.rs
+++ b/crates/fj-operations/src/transform.rs
@@ -13,7 +13,7 @@ impl Shape for fj::Transform {
 
     fn compute_brep(
         &self,
-        objects: &Objects,
+        objects: &mut Objects,
         debug_info: &mut DebugInfo,
     ) -> Result<Self::Brep, ValidationError> {
         let faces = self