"Keys"

at 100% piano keys will be typical full sized 88 key piano keyboard.

at 100% drywall screw heads fit into recesses on the back.

The measurement markings are for those who have multiple colored printers.  (they won't show up unless you paint them in prusa slicer)

print white keys upside down for nice smooth keyboard.

I'll take the time to work on downsizing it a bit, including a single file for multicolor printing and any other suggestions.