diff --git a/CMakeLists.txt b/CMakeLists.txt
new file mode 100644
index 0000000..9d6dfc5
--- /dev/null
+++ b/CMakeLists.txt
@@ -0,0 +1,13 @@
+cmake_minimum_required(VERSION 4.2)
+project(j7s_diagnostics_py)
+
+find_package(ament_cmake REQUIRED)
+
+add_custom_target(build_info ALL)
+add_custom_command(TARGET build_info
+                   POST_BUILD
+                   COMMAND ${CMAKE_CURRENT_SOURCE_DIR}/build.py --install-path ${CMAKE_INSTALL_PREFIX} --build-dir ${PROJECT_BINARY_DIR} --src-dir ${CMAKE_CURRENT_SOURCE_DIR}
+                   WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
+)
+
+ament_package()
diff --git a/build.py b/build.py
new file mode 100755
index 0000000..5632bac
--- /dev/null
+++ b/build.py
@@ -0,0 +1,48 @@
+#!/usr/bin/env python3
+#
+# Copyright 2026 James Pace
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at https://mozilla.org/MPL/2.0/.
+#
+# This Source Code Form is "Incompatible With Secondary Licenses", as
+# defined by the Mozilla Public License, v. 2.0.
+#
+import argparse
+import subprocess
+import venv
+from pathlib import Path
+
+# The build for this is a little funky.
+# Maturin only plays nice with pyproject.toml style configs.
+# ROS2 is the opposite.
+# So... We setup an venv, pip install into it (which plays nice with pyproject.toml).
+# Then we copy the result to the right place for ament/ros2.
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument("--src-dir", type=str)
+    parser.add_argument("--build-dir", type=str)
+    parser.add_argument("--install-path", type=str)
+    args = parser.parse_args()
+
+    build(args.src_dir, args.build_dir, args.install_path)
+
+def build(source_directory, build_directory, install_directory):
+    # Make a venv in the build_directory.
+    builder = venv.EnvBuilder(system_site_packages=True, with_pip=True, prompt="")
+    venv_directory = Path(build_directory) / "venv"
+    builder.create(venv_directory)
+
+    # activate it and call pip install.
+    command = f". {venv_directory}/bin/activate && pip install {source_directory}"
+    subprocess.run(command, shell=True)
+
+    # copy the result to the install directory.
+    command = f"cp -r {venv_directory}/lib {install_directory}"
+    subprocess.run(command, shell=True)
+
+
+if __name__ == "__main__":
+    main()
diff --git a/package.xml b/package.xml
new file mode 100644
index 0000000..cd254e8
--- /dev/null
+++ b/package.xml
@@ -0,0 +1,16 @@
+<?xml version="1.0"?>
+<?xml-model href="http://download.ros.org/schema/package_format2.xsd" schematypens="http://www.w3.org/2001/XMLSchema"?>
+<package format="2">
+  <name>j7s_diagnostics_py</name>
+  <version>0.0.1</version>
+  <description>TODO</description>
+  <license>MPL 2.0</license>
+  <author email="jpace121@gmail.com">James Pace</author>
+  <maintainer email="jpace121@gmail.com">James Pace</maintainer>
+
+  <buildtool_depend>ament_cmake</buildtool_depend>
+
+  <export>
+    <build_type>ament_cmake</build_type>
+  </export>
+</package>
diff --git a/src/lib.rs b/src/lib.rs
index 3dc7c5f..754e496 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -3,7 +3,6 @@ use pyo3::prelude::*;
 use pyo3::types::{PyDict, PyString};
 use std::collections::BTreeMap;
 
-/// A Python module implemented in Rust.
 #[pymodule]
 mod j7s_diagnostics_py {
     #[pymodule_export]