snakehouse
snakehouse is a tool to pack mutiple .pyx files into a single extension.
Inspired by this StackOverflow discussion.
Tested and works on CPython 3.5-3.9, both Windows and Linux. Somehow, it seems to pass unit tests on PyPy, so I enabled installation at PyPy, but I would seem to be vary of that. Please report your results by raising an issue.
READ BEFORE YOU USE
Be sure to read the docs before you start using it.