diff --git a/spinoffs/fun_mc/pyproject.toml b/spinoffs/fun_mc/pyproject.toml
new file mode 100644
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+++ b/spinoffs/fun_mc/pyproject.toml
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+# Copyright 2024 The TensorFlow Probability Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+[build-system]
+requires = ["setuptools >= 61.0"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "fun_mc"
+description = "Functional MC: A functional API for creating new Markov Chains."
+version = "0.1.0"
+dependencies = [
+    "immutabledict",
+    "numpy>=1.13.3",
+]
+requires-python = ">= 3.10"
+authors = [
+    {name="Google LLC", email="no-reply@google.com"},
+]
+classifiers = [
+    "Development Status :: 4 - Beta",
+    "Intended Audience :: Developers",
+    "Intended Audience :: Education",
+    "Intended Audience :: Science/Research",
+    "License :: OSI Approved :: Apache Software License",
+    "Programming Language :: Python :: 3",
+    "Programming Language :: Python :: 3.10",
+    "Topic :: Scientific/Engineering",
+    "Topic :: Scientific/Engineering :: Mathematics",
+    "Topic :: Scientific/Engineering :: Artificial Intelligence",
+    "Topic :: Software Development",
+    "Topic :: Software Development :: Libraries",
+    "Topic :: Software Development :: Libraries :: Python Modules",
+]
+keywords = [
+    "markov chain monte carlo",
+]