diff --git a/crates/fj/src/handle_model.rs b/crates/fj/src/handle_model.rs
index 407c456e1..53c1ed1ee 100644
--- a/crates/fj/src/handle_model.rs
+++ b/crates/fj/src/handle_model.rs
@@ -1,9 +1,12 @@
 use std::ops::Deref;
 
-use fj_core::algorithms::{
-    approx::{InvalidTolerance, Tolerance},
-    bounding_volume::BoundingVolume,
-    triangulate::Triangulate,
+use fj_core::{
+    algorithms::{
+        approx::{InvalidTolerance, Tolerance},
+        bounding_volume::BoundingVolume,
+        triangulate::Triangulate,
+    },
+    services::Services,
 };
 use fj_interop::model::Model;
 use fj_math::{Aabb, Point, Scalar};
@@ -18,13 +21,21 @@ use crate::Args;
 ///
 /// This function is used by Fornjot's own testing infrastructure, but is useful
 /// beyond that, when using Fornjot directly to define a model.
-pub fn handle_model<M>(model: impl Deref<Target = M>) -> Result
+pub fn handle_model<M>(
+    model: impl Deref<Target = M>,
+    services: Services,
+) -> Result
 where
     for<'r> (&'r M, Tolerance): Triangulate,
     M: BoundingVolume<3>,
 {
     let args = Args::parse();
 
+    // Dropping `Services` will cause a panic, if there are any unhandled
+    // validation errors. It would be better to return an error, but this will
+    // do for now.
+    drop(services);
+
     let aabb = model.aabb().unwrap_or(Aabb {
         min: Point::origin(),
         max: Point::origin(),
diff --git a/models/all/src/main.rs b/models/all/src/main.rs
index 27e7d3073..d41417248 100644
--- a/models/all/src/main.rs
+++ b/models/all/src/main.rs
@@ -1,7 +1,8 @@
 use fj::{core::services::Services, handle_model};
 
 fn main() -> fj::Result {
-    let model = all::model(&mut Services::new());
-    handle_model(model)?;
+    let mut services = Services::new();
+    let model = all::model(&mut services);
+    handle_model(model, services)?;
     Ok(())
 }
diff --git a/models/cuboid/src/main.rs b/models/cuboid/src/main.rs
index 6b9fdc21f..23edaa890 100644
--- a/models/cuboid/src/main.rs
+++ b/models/cuboid/src/main.rs
@@ -1,7 +1,8 @@
 use fj::{core::services::Services, handle_model};
 
 fn main() -> fj::Result {
-    let model = cuboid::model(3., 2., 1., &mut Services::new());
-    handle_model(model)?;
+    let mut services = Services::new();
+    let model = cuboid::model(3., 2., 1., &mut services);
+    handle_model(model, services)?;
     Ok(())
 }
diff --git a/models/spacer/src/main.rs b/models/spacer/src/main.rs
index 18bf6af09..64ed2d1d4 100644
--- a/models/spacer/src/main.rs
+++ b/models/spacer/src/main.rs
@@ -1,7 +1,8 @@
 use fj::{core::services::Services, handle_model};
 
 fn main() -> fj::Result {
-    let model = spacer::model(1., 0.5, 1., &mut Services::new());
-    handle_model(model)?;
+    let mut services = Services::new();
+    let model = spacer::model(1., 0.5, 1., &mut services);
+    handle_model(model, services)?;
     Ok(())
 }
diff --git a/models/star/src/main.rs b/models/star/src/main.rs
index 32a8f8a8d..6022870fe 100644
--- a/models/star/src/main.rs
+++ b/models/star/src/main.rs
@@ -1,7 +1,8 @@
 use fj::{core::services::Services, handle_model};
 
 fn main() -> fj::Result {
-    let model = star::model(5, 1., 2., 1., &mut Services::new());
-    handle_model(model)?;
+    let mut services = Services::new();
+    let model = star::model(5, 1., 2., 1., &mut services);
+    handle_model(model, services)?;
     Ok(())
 }