Care to share a bit more detail on how you did this? Was there some interfacing library that you used analogous to Cython/SWIG/etc.? Presumably you didn't code directly against the C API (in python.h)?
The rust library interfacing with python is https://github.com/dgrunwald/rust-cpython This library understand things like python arrays, objects, etc. and provides nice rust interfaces to them. Basically I just have to write a macro that specifies what functions I'm exposing to python, and other then that I'm writing normal rust. On the python side I'm importing them and calling them like any other python library.
The build system is https://github.com/PyO3/setuptools-rust (which is linked at the bottom of the above readme).