While perusing the other Hackaday Prize entries for this year, I noticed that there is an open source version of the blue-pill board that I'm using for this project! The "green pill" is by open-plc.com.

I followed the links over to GitHub, where I discovered that, while they published PDFs and Gerbers, the original board and schematic files from design software were not in it. So I can't make a nice 3d render of the board, or add modifications, or incorporate it into my own designs or anything.

So "open", but no usable "source". C'est la vie.

I sent a message asking for the sources to be posted. Maybe they will do it?