This project is a mounting box for a power switch. It is designed to suit a 12mm x 20mm power switch.
Included is a strain relief for the cables, a zip tie can be used to fix the cables in place.
Two of the screws for the Z-axis motor are re-used. You will need an extra 3mm or 4mm screw (at least 13mm long) and nut.
For a suitable switch, see www.dx.com/p/256020