Toggle Switch Guard

This is to keep from accidentally flipping a toggle switch. In this case I intend to use it with a 1/2 hp 90V DC Permanent Magnet motor to control the rotation direction, if it is running and accidentally switched - bad things may happen to the motor or motor control (the magic smoke may get out of the wires).
This is for a toggle switch with a 12 mm stem and 16 mm nut (turned out to be 15 mm nut). In my case this is a NKK Toggle Switch S332T-RO.
There is clearance to put a deep well socket