Stephen White's Pi1541 project: https://cbm-pi1541.firebaseapp.com/

There are many Pi hats based on that project, and the particular one I have is a kit from https://store.ribit.se/egna-produkter/pi1541.html

The case openings are modeled after a RPi 2 model B.

Everything is snap fit. Do not glue the buttons to the top even of it looks like they are made for that. To compensate for inexact distance between the top and the microswitches the buttons should be left floating on top of the switches for best feel and responsiveness.

The button holes have a small margin, but due to the nature of FDM printing probably not enough. Ream them with a 3.5mm drill bit to get a good fit.

The top, bottom and buttons are printable without supports. The shroud should be printed with supports, on a raft and with the legs down. A cutoff angle of 55 degree supports the roof without attaching any hard to clean areas.