I just ordered 10 copies of version 1.1 of the board. The layout changed a fair bit to make it a bit more compact, but I only took a few mm off one side - the rest of the savings went to a header to make it easier to use the outside row of pins of the Pi Pico.
I also made some significant progress on converting the RPM calculation from a bodge to a more organized structure that can do tricks like rolling averages. Turns out serial communication over USB in MicroPython is a bit of a bodge itself, though, so that will take some effort.
Should be a few weeks before the new boards are in and I can build one up, but I’m pretty confident in them.
I’m less certain about how to approach the input cover slot. I saw Arya’s input connector shim project (Input connector shim - for power switch, USB 2.0 and LEDs) and that would work, but it’s very minimalist and not quite suited for what I want to do. I think a rigid board might be the way to go, but rather than have it quite so compact, have it extend off the side for some different options in connector plugs and orientation. It would still be a small board overall.
The local library is printing my PCIe slot adapter. Could probably make it easier to print on a home printer with some redesign (it’s really long, especially because I wanted to keep the modular slots on one side and needed room for those) but I am not much of a mechanical guy, so electrical side first.