The adapter is made to fit a Durst Comot darkroom paper development machine, which is why the smaller cutout for the switch is slightly offset in the larger hole. You may adapt the innerOffset variable in the .scad file, if you need another orientation. The file needs BOSL2.

The small switch is a standard 8 x 15mm size. The switch itself is press-fit via the small hooks in the switch, while the Adapter is clipped in between two halves of the housing.

Print on a large flat side, with supports between the two halves. Or use the 3mf file. I printed in PLA, works perfectly fine.