diff --git a/Cargo.lock b/Cargo.lock
index 316cc723c..dc963a304 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -629,10 +629,7 @@ dependencies = [
 name = "cuboid"
 version = "0.1.0"
 dependencies = [
- "anyhow",
- "clap",
  "fj",
- "itertools",
 ]
 
 [[package]]
@@ -781,12 +778,14 @@ dependencies = [
 name = "fj"
 version = "0.46.0"
 dependencies = [
+ "clap",
  "fj-core",
  "fj-export",
  "fj-interop",
  "fj-math",
  "fj-viewer",
  "fj-window",
+ "thiserror",
 ]
 
 [[package]]
diff --git a/crates/fj-window/src/lib.rs b/crates/fj-window/src/lib.rs
index 0a317a64b..1b0d14de4 100644
--- a/crates/fj-window/src/lib.rs
+++ b/crates/fj-window/src/lib.rs
@@ -13,4 +13,4 @@
 mod run;
 mod window;
 
-pub use self::run::run;
+pub use self::run::{run, Error};
diff --git a/crates/fj/Cargo.toml b/crates/fj/Cargo.toml
index 4d007ffdf..987895b85 100644
--- a/crates/fj/Cargo.toml
+++ b/crates/fj/Cargo.toml
@@ -10,6 +10,7 @@ license.workspace = true
 keywords.workspace = true
 categories.workspace = true
 
+
 [dependencies]
 fj-core.workspace = true
 fj-export.workspace = true
@@ -17,3 +18,8 @@ fj-interop.workspace = true
 fj-math.workspace = true
 fj-viewer.workspace = true
 fj-window.workspace = true
+thiserror = "1.0.40"
+
+[dependencies.clap]
+version = "4.3.1"
+features = ["derive"]
diff --git a/crates/fj/src/args.rs b/crates/fj/src/args.rs
new file mode 100644
index 000000000..bf8566764
--- /dev/null
+++ b/crates/fj/src/args.rs
@@ -0,0 +1,19 @@
+use std::path::PathBuf;
+
+/// Standardized CLI for Fornjot models
+#[derive(clap::Parser)]
+pub struct Args {
+    /// Export model to this path
+    #[arg(short, long, value_name = "PATH")]
+    pub export: Option<PathBuf>,
+}
+
+impl Args {
+    /// Parse the command-line arguments
+    ///
+    /// Convenience method that saves the caller from having to import the
+    /// `clap::Parser` trait.
+    pub fn parse() -> Self {
+        <Self as clap::Parser>::parse()
+    }
+}
diff --git a/crates/fj/src/handle_model.rs b/crates/fj/src/handle_model.rs
new file mode 100644
index 000000000..5fca60f3e
--- /dev/null
+++ b/crates/fj/src/handle_model.rs
@@ -0,0 +1,47 @@
+use std::ops::Deref;
+
+use fj_core::algorithms::{approx::Tolerance, triangulate::Triangulate};
+
+use crate::Args;
+
+/// Export or display a model, according to CLI arguments
+///
+/// This function is intended to be called by applications that define a model
+/// and want to provide a standardized CLI interface for dealing with that
+/// model.
+///
+/// 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<Model>(
+    model: impl Deref<Target = Model>,
+    tolerance: impl Into<Tolerance>,
+) -> Result
+where
+    for<'r> (&'r Model, Tolerance): Triangulate,
+{
+    let mesh = (model.deref(), tolerance.into()).triangulate();
+
+    let args = Args::parse();
+    if let Some(path) = args.export {
+        crate::export::export(&mesh, &path)?;
+    } else {
+        crate::window::run(mesh, false)?;
+    }
+
+    Ok(())
+}
+
+/// Return value of [`handle_model`]
+pub type Result = std::result::Result<(), Error>;
+
+/// Error returned by [`handle_model`]
+#[derive(Debug, thiserror::Error)]
+pub enum Error {
+    /// Error displaying model
+    #[error("Error displaying model")]
+    Display(#[from] crate::window::Error),
+
+    /// Error exporting model
+    #[error("Error exporting model")]
+    Export(#[from] crate::export::Error),
+}
diff --git a/crates/fj/src/lib.rs b/crates/fj/src/lib.rs
index 1df53c170..8224c3599 100644
--- a/crates/fj/src/lib.rs
+++ b/crates/fj/src/lib.rs
@@ -11,6 +11,14 @@
 
 #![warn(missing_docs)]
 
+mod args;
+mod handle_model;
+
+pub use self::{
+    args::Args,
+    handle_model::{handle_model, Error, Result},
+};
+
 pub use fj_core as core;
 pub use fj_export as export;
 pub use fj_interop as interop;
diff --git a/models/cuboid/Cargo.toml b/models/cuboid/Cargo.toml
index 09a5bd5dd..42746d61c 100644
--- a/models/cuboid/Cargo.toml
+++ b/models/cuboid/Cargo.toml
@@ -3,14 +3,5 @@ name = "cuboid"
 version = "0.1.0"
 edition = "2021"
 
-
-[dependencies]
-anyhow = "1.0.71"
-itertools = "0.10.5"
-
-[dependencies.clap]
-version = "4.3.1"
-features = ["derive"]
-
 [dependencies.fj]
 path = "../../crates/fj"
diff --git a/models/cuboid/src/main.rs b/models/cuboid/src/main.rs
index 51a03f31f..3fbe0d285 100644
--- a/models/cuboid/src/main.rs
+++ b/models/cuboid/src/main.rs
@@ -1,41 +1,12 @@
-use std::{ops::Deref, path::PathBuf};
-
-use fj::core::algorithms::{approx::Tolerance, triangulate::Triangulate};
-
-fn main() -> anyhow::Result<()> {
-    let args = Args::parse();
+use fj::handle_model;
 
+fn main() -> fj::Result {
     let cuboid = cuboid::cuboid(3., 2., 1.);
 
     // The tolerance makes no difference for this model, as there aren't any
     // curves.
-    let tolerance = Tolerance::from_scalar(1.)?;
-
-    let mesh = (cuboid.deref(), tolerance).triangulate();
-
-    if let Some(path) = args.export {
-        fj::export::export(&mesh, &path)?;
-    } else {
-        fj::window::run(mesh, false)?;
-    }
+    let tolerance = 1.;
+    handle_model(cuboid, tolerance)?;
 
     Ok(())
 }
-
-/// Standardized CLI for Fornjot models
-#[derive(clap::Parser)]
-pub struct Args {
-    /// Export model to this path
-    #[arg(short, long, value_name = "PATH")]
-    pub export: Option<PathBuf>,
-}
-
-impl Args {
-    /// Parse the command-line arguments
-    ///
-    /// Convenience method that saves the caller from having to import the
-    /// `clap::Parser` trait.
-    pub fn parse() -> Self {
-        <Self as clap::Parser>::parse()
-    }
-}