diff --git a/crates/fj-core/src/operations/merge.rs b/crates/fj-core/src/operations/merge.rs
new file mode 100644
index 000000000..968a6b3c5
--- /dev/null
+++ b/crates/fj-core/src/operations/merge.rs
@@ -0,0 +1,15 @@
+use crate::objects::Solid;
+
+use super::UpdateSolid;
+
+/// Merge two [`Solid`]s
+pub trait Merge {
+    /// Merge this solid with another
+    fn merge(&self, other: &Self) -> Self;
+}
+
+impl Merge for Solid {
+    fn merge(&self, other: &Self) -> Self {
+        self.add_shells(other.shells().cloned())
+    }
+}
diff --git a/crates/fj-core/src/operations/mod.rs b/crates/fj-core/src/operations/mod.rs
index 5d43064e4..3cd87865a 100644
--- a/crates/fj-core/src/operations/mod.rs
+++ b/crates/fj-core/src/operations/mod.rs
@@ -3,6 +3,7 @@
 mod build;
 mod insert;
 mod join;
+mod merge;
 mod reverse;
 mod update;
 
@@ -19,6 +20,7 @@ pub use self::{
     },
     insert::{Insert, IsInserted, IsInsertedNo, IsInsertedYes},
     join::cycle::JoinCycle,
+    merge::Merge,
     reverse::Reverse,
     update::{
         cycle::UpdateCycle, edge::UpdateHalfEdge, face::UpdateFace,