diff --git a/.gitattributes b/.gitattributes
new file mode 100644
index 0000000..8f61a8e
--- /dev/null
+++ b/.gitattributes
@@ -0,0 +1,2 @@
+# SCM syntax highlighting
+pixi.lock linguist-language=YAML linguist-generated=true
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..740bb7d
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,4 @@
+
+# pixi environments
+.pixi
+*.egg-info
diff --git a/pyproject.toml b/pyproject.toml
new file mode 100644
index 0000000..ae9bcf6
--- /dev/null
+++ b/pyproject.toml
@@ -0,0 +1,17 @@
+[project]
+authors = [{ name = "quantity-dev contributors" }]
+dependencies = []
+name = "dimension-api"
+requires-python = ">= 3.12"
+version = "0.0.1.dev0"
+
+[build-system]
+build-backend = "hatchling.build"
+requires = ["hatchling"]
+
+[tool.pixi.project]
+channels = ["https://prefix.dev/conda-forge"]
+platforms = ["win-64", "linux-64", "osx-64", "osx-arm64"]
+
+[tool.pixi.pypi-dependencies]
+dimension_api = { path = ".", editable = true }
diff --git a/src/dimension_api/__init__.py b/src/dimension_api/__init__.py
new file mode 100644
index 0000000..0885dc2
--- /dev/null
+++ b/src/dimension_api/__init__.py
@@ -0,0 +1,12 @@
+"""Dimension API."""
+
+from typing import Final, Protocol, Self, runtime_checkable
+
+__version__: Final = "0.0.1.dev0"
+__all__ = ["__version__", "Dimension"]
+
+@runtime_checkable
+class Dimension(Protocol):
+    def __mul__(self, other: Self, /) -> Self: ...
+    def __truediv__(self, other: Self, /) -> Self: ...
+    def __pow__(self, other: int, /) -> Self: ...