This case was made to protect a Raspberry PI Zero with the Domoshop Slim MIDI hat. You can make a very compact MIDI processor this way. The top cut was made so that you can use the I/O connector. Maybe I should add a cut for the I2C port to integrate a small OLED display?

3D printer or laser cutter with the SVG files below.

For spacer, I suggest using 9mm spacers (or 8mm + 1mm washer) for the 1st level. And 5mm spacers between the Hat and the top plate.