This is a small case for a emergency stop button with 16mm shaft diameter.
The bottom hole spacing is 20mm, so it fits to aluminum profiles like V-slot or similar.
What you need:

• two M5 x 10mm screws
• four 2,9 x 9,6mm tapping screws.

After slicing the top part of the model you should get one closed layer. It works like a bridge layer. I’ve made this to print a clean hole for the switch on the top of it. This way, the model can be printed without printing additional supports.
Since the closed layer is only one layer thick, it can easily be removed with a knife or just with the finger.