I don't understand. - What you are showing is the Pi Multiselector which is an addon for the IDE V2 (and V3) - Why add another PCB (which does not add any more functionality and only extends)?
Why add another PCB and not add the components (Buttons, LED etc) directly to the 3d Printed file? - all connectivity is already given on the V3 PCB
... only what is missing is a reset button (i gues that is just a button connected to the motherboard?)
There are already 3D files for the Pi Multiselector (for V3) on this thread:
https://www.arcade-projects.com/thr...de-v3-modifications-and-new-rpi-images.34778/ - If that is something you are looking for
As far as i understand the Pi Multiselector only adds a more "on the fly" key change behaviour to the setup - and my understanding is that there are solutions in the works where we dont need the pi selector any more)