diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index b8fba639..d5e8f5d0 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -5,9 +5,7 @@ on:
   pull_request:
   push:
     branches:
-    - master
     - main
-    - develop
 
 jobs:
   pre-commit:
@@ -15,7 +13,6 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v2
-    - uses: actions/setup-python@v2
 
     - name: Lint setuptools
       run: pipx run nox --forcecolor -s 'lint(setuptools)'
@@ -23,11 +20,17 @@ jobs:
     - name: Lint pybind11
       run: pipx run nox --forcecolor -s 'lint(pybind11)'
 
+    - name: Lint poetry
+      run: pipx run nox --forcecolor -s 'lint(poetry)'
+
     - name: Lint flit
       run: pipx run nox --forcecolor -s 'lint(flit)'
 
-    - name: Lint poetry
-      run: pipx run nox --forcecolor -s 'lint(poetry)'
+    - name: Lint flit621
+      run: pipx run nox --forcecolor -s 'lint(flit621)'
+
+    - name: Lint trampolim
+      run: pipx run nox --forcecolor -s 'lint(trampolim)'
 
 
   checks:
@@ -60,11 +63,18 @@ jobs:
     - name: Test pybind11
       run: nox --forcecolor -s 'tests(pybind11)'
 
+    - name: Test poetry
+      run: nox --forcecolor -s 'tests(poetry)'
+
     - name: Test flit
       run: nox --forcecolor -s 'tests(flit)'
 
-    - name: Test poetry
-      run: nox --forcecolor -s 'tests(poetry)'
+    - name: Test flit621
+      run: nox --forcecolor -s 'tests(flit621)'
+
+    - name: Test trampolim
+      if: matrix.python-version != '3.6'
+      run: nox --forcecolor -s 'tests(trampolim)'
 
     - name: Test poetry tooling
       run: nox --forcecolor -s tests_poetry
diff --git a/README.md b/README.md
index 33cb7cc2..5772392e 100644
--- a/README.md
+++ b/README.md
@@ -28,6 +28,9 @@ This is a Python template project, with the following project types:
 4. [poetry][]: An all-in-one solution to pure Python projects. Replaces setuptools,
    venv/pipenv, pip, wheel, and twine. Higher learning curve, but is
    all-in-one.
+5. [flit621][flit]: Flit, but with PEP 621 style configuration (hidden feature).
+6. [trampolim][]: A modern PEP 621 builder with support for tasks, allowing
+   arbitrary Python to run during the build process if needed.
 
 #### To use:
 
@@ -118,4 +121,5 @@ If you don't have `nox` locally, you can use [pipx][], such as `pipx run nox` in
 [poetry]:       https://python-poetry.org
 [pybind11]:     https://pybind11.readthedocs.io/en/stable/
 [setuptools]:   https://setuptools.readthedocs.io/en/latest/
+[trampolim]:    https://trampolim.readthedocs.io/en/latest/
 [pipx]:         https://pypa.github.io/pipx/
diff --git a/cookiecutter.json b/cookiecutter.json
index a57f9738..11c6d06c 100644
--- a/cookiecutter.json
+++ b/cookiecutter.json
@@ -3,7 +3,7 @@
     "org": "Scikit-HEP",
     "url": "https://github.com/{{ cookiecutter.org }}/{{ cookiecutter.project_name }}",
     "full_name": "My Name",
-    "project_type": ["setuptools", "pybind11", "flit", "poetry"],
+    "project_type": ["setuptools", "pybind11", "poetry", "flit", "flit621", "trampolim"],
     "email": "me@email.com",
     "maintainer": "The Scikit-HEP admins",
     "maintainer_email": "scikit-hep-admins@googlegroups.com",
diff --git a/hooks/post_gen_project.py b/hooks/post_gen_project.py
index fc63d58f..ab9eff81 100644
--- a/hooks/post_gen_project.py
+++ b/hooks/post_gen_project.py
@@ -2,14 +2,16 @@
 
 project_name = "{{ cookiecutter.project_name }}"
 project_type = "{{ cookiecutter.project_type }}"
-project_types = {"setuptools", "pybind11", "flit", "poetry"}
+project_types = {"setuptools", "pybind11", "poetry", "flit", "flit621", "trampolim"}
 other_project_types = project_types - {project_type}
 
 project_underscore_name = project_name.replace("-", "_")
 project_dash_name = project_name.replace("_", "-")
 
+src = Path("src")
+
 if project_name != project_underscore_name:
-    Path(f"src/{project_name}").rename(f"src/{project_underscore_name}")
+    (src / project_name).rename(src / project_underscore_name)
 
 files = [p for p in Path(".").rglob("*") if p.is_file() and "-" in p.stem]
 
@@ -21,3 +23,10 @@
         f.replace(f.with_name(f"{base}{f.suffix}"))
     elif currents & other_project_types:
         f.unlink()
+
+# Hackaround lack of "src/" support in trampolim - remove when proper support
+# is added (and maybe after editable support is added?)
+# Also remove if clause in .pre-commit-config.yaml
+if project_type == "trampolim":
+    for f in Path("src").iterdir():
+        f.rename(f.stem)
diff --git a/noxfile.py b/noxfile.py
index 6d6a6f3a..592ac0ee 100644
--- a/noxfile.py
+++ b/noxfile.py
@@ -1,9 +1,8 @@
 import nox
 from pathlib import Path
-import shutil
 
 DIR = Path(__file__).parent.resolve()
-BACKENDS = "setuptools", "pybind11", "flit", "poetry"
+BACKENDS = "setuptools", "pybind11", "poetry", "flit", "flit621", "trampolim"
 
 JOB_FILE = """\
 default_context:
@@ -11,6 +10,8 @@
   project_type: {backend}
 """
 
+ENV = {"SETUPTOOLS_SCM_PRETEND_VERSION": "0.1.0"}
+
 
 def make_cookie(session: nox.Session, backend: str) -> str:
     tmp_dir = session.create_tmp()
@@ -45,7 +46,7 @@ def lint(session: nox.Session, backend: str) -> None:
         "../tmp_git",
         external=True,
     )
-    shutil.move("../tmp_git/.git", ".git")
+    Path("../tmp_git/.git").rename(".git")
     session.run("git", "add", ".", external=True)
 
     session.run(
@@ -64,7 +65,7 @@ def tests(session, backend):
 
     make_cookie(session, backend)
 
-    session.install(".[test]", env={"SETUPTOOLS_SCM_PRETEND_VERSION": "0.1.0"})
+    session.install(".[test]", env=ENV)
     session.run("python", "-m", "pytest", "-ra")
 
 
@@ -85,14 +86,18 @@ def dist(session, backend):
 
     make_cookie(session, backend)
 
-    session.run(
-        "python", "-m", "build", env={"SETUPTOOLS_SCM_PRETEND_VERSION": "0.1.0"}
-    )
-    files = list(Path("dist").iterdir())
+    session.run("python", "-m", "build", env=ENV)
+    (sdist,) = Path("dist").glob("*.tar.gz")
+    (wheel,) = Path("dist").glob("*.whl")
+
+    if "0.1.0" not in str(wheel):
+        session.error(f"{wheel} must be version 0.1.0")
 
-    session.run("twine", "check", *(str(f) for f in files))
+    # Twine only supports metadata 2.1, trampoline produces metadata 2.2
+    if backend != "trampolim":
+        session.run("twine", "check", str(sdist), str(wheel))
 
-    for f in files:
-        dist = DIR / "dist"
-        dist.mkdir(exist_ok=True)
-        shutil.move(str(f), str(dist))
+    dist = DIR / "dist"
+    dist.mkdir(exist_ok=True)
+    sdist.rename(dist / sdist.stem)
+    wheel.rename(dist / wheel.stem)
diff --git a/{{cookiecutter.project_name}}/.github/workflows/ci-trampolim.yml b/{{cookiecutter.project_name}}/.github/workflows/ci-trampolim.yml
new file mode 100644
index 00000000..045b0430
--- /dev/null
+++ b/{{cookiecutter.project_name}}/.github/workflows/ci-trampolim.yml
@@ -0,0 +1,80 @@
+
+name: CI
+
+on:
+  workflow_dispatch:
+  pull_request:
+  push:
+    branches:
+    - master
+    - main
+    - develop
+  release:
+    types:
+      - published
+
+jobs:
+  pre-commit:
+    name: Format
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v1
+    - uses: actions/setup-python@v2
+    - uses: pre-commit/action@v2.0.3
+      with:
+        extra_args: --hook-stage manual --all-files
+
+  checks:
+    name: Check Python ${{ matrix.python-version }} on ${{ matrix.runs-on }}
+    runs-on: ${{ matrix.runs-on }}
+    needs: [pre-commit]
+    strategy:
+      fail-fast: false
+      matrix:
+        python-version: [3.6, 3.9]
+        runs-on: [ubuntu-latest, macos-latest, windows-latest]
+
+        include:
+        - python-version: pypy-3.7
+          runs-on: ubuntu-latest
+
+
+    steps:
+    - uses: actions/checkout@v2
+
+    - uses: actions/setup-python@v2
+      with:
+        python-version: ${{ matrix.python-version }}
+
+    - name: Install package
+      run: python -m pip install .[test]
+
+    - name: Test package
+      run: python -m pytest -ra
+
+
+  dist:
+    name: Distribution build
+    runs-on: ubuntu-latest
+    needs: [pre-commit]
+
+    steps:
+    - uses: actions/checkout@v1
+
+    - name: Build sdist and wheel
+      run: pipx run build
+
+    - uses: actions/upload-artifact@v2
+      with:
+        path: dist
+
+    - uses: pypa/gh-action-pypi-publish@v1.4.2
+      if: github.event_name == 'release' && github.event.action == 'published'
+      with:
+        user: __token__
+        # Remember to generate this and set it in "GitHub Secrets"
+        password: ${{ secrets.pypi_password }}
+        # Remove this line
+        repository_url: https://test.pypi.org/legacy/
+        # Check not supported currently by twine + trampolim
+        verify_metadata: false
diff --git a/{{cookiecutter.project_name}}/.github/workflows/ci.yml b/{{cookiecutter.project_name}}/.github/workflows/ci.yml
index c1f8ccf1..972784eb 100644
--- a/{{cookiecutter.project_name}}/.github/workflows/ci.yml
+++ b/{{cookiecutter.project_name}}/.github/workflows/ci.yml
@@ -67,6 +67,9 @@ jobs:
       with:
         path: dist
 
+    - name: Check products
+      run: pip run twine check dist/*
+
     - uses: pypa/gh-action-pypi-publish@v1.4.2
       if: github.event_name == 'release' && github.event.action == 'published'
       with:
diff --git a/{{cookiecutter.project_name}}/.pre-commit-config.yaml b/{{cookiecutter.project_name}}/.pre-commit-config.yaml
index a5516403..2c25f947 100644
--- a/{{cookiecutter.project_name}}/.pre-commit-config.yaml
+++ b/{{cookiecutter.project_name}}/.pre-commit-config.yaml
@@ -49,7 +49,11 @@ repos:
   rev: v0.901
   hooks:
   - id: mypy
+    {%- if cookiecutter.project_type == "trampolim" %}
+    files: {{ cookiecutter.project_name }}
+    {%- else %}
     files: src
+    {%- endif %}
 
 {%- if cookiecutter.project_type == "setuptools" or cookiecutter.project_type == "pybind11" %}
 
diff --git a/{{cookiecutter.project_name}}/pyproject-flit621,trampolim.toml b/{{cookiecutter.project_name}}/pyproject-flit621,trampolim.toml
new file mode 100644
index 00000000..bcade722
--- /dev/null
+++ b/{{cookiecutter.project_name}}/pyproject-flit621,trampolim.toml
@@ -0,0 +1,87 @@
+[build-system]
+{%- if cookiecutter.project_type == "trampolim" %}
+requires = ['trampolim ~=0.0.3']
+build-backend = 'trampolim'
+{%- else %}
+requires = ['flit_core ~=3.2']
+build-backend = 'flit_core.buildapi'
+{%- endif %}
+
+[project]
+name = "{{ cookiecutter.project_name.replace("-", "_") }}"
+authors = [
+  { name = "{{ cookiecutter.full_name }}", email = "{{ cookiecutter.email }}" },
+]
+maintainers = [
+  { name = "{{ cookiecutter.maintainer }}", email = "{{ cookiecutter.maintainer_email }}" },
+]
+license = { file = "LICENSE" }
+
+version = "0.1.0"
+description = "{{ cookiecutter.project_short_description }}"
+readme = "README.md"
+
+requires-python = ">=3.6"
+
+classifiers = [
+  "License :: OSI Approved :: BSD License",
+  "Topic :: Scientific/Engineering",
+  "Intended Audience :: Science/Research",
+  "Intended Audience :: Developers",
+  "Operating System :: OS Independent",
+  "License :: OSI Approved :: BSD License",
+  "Programming Language :: Python",
+  "Programming Language :: Python :: 3",
+  "Programming Language :: Python :: 3.6",
+  "Programming Language :: Python :: 3.7",
+  "Programming Language :: Python :: 3.8",
+  "Programming Language :: Python :: 3.9",
+  "Development Status :: 1 - Planning",
+]
+
+dependencies = [
+  "numpy >=1.13.3",
+  "typing; python_version<'3.5'",
+]
+
+[project.optional-dependencies]
+test = [
+    "pytest >=6",
+]
+dev = [
+  "pytest >=6",
+]
+docs = [
+  "Sphinx >=3.0.0",
+  "myst_parser>=0.13",
+  "sphinx-book-theme>=0.0.33",
+  "sphinx_copybutton",
+]
+
+[project.urls]
+homepage = "{{ cookiecutter.url }}"
+
+
+[tool.pytest.ini_options]
+addopts = "-ra -Wd"
+testpaths = ["tests"]
+
+
+[tool.mypy]
+files = "src"
+python_version = "3.6"
+warn_unused_configs = true
+
+disallow_any_generics = true
+disallow_subclassing_any = true
+disallow_untyped_calls = true
+disallow_untyped_defs = true
+disallow_incomplete_defs = true
+check_untyped_defs = true
+disallow_untyped_decorators = true
+no_implicit_optional = true
+warn_redundant_casts = true
+warn_unused_ignores = true
+warn_return_any = true
+no_implicit_reexport = true
+strict_equality = true