One solution is to incorporate a cover plate on the disc.
This cover plate can be removed for painting, without the use of tools.
I pressed in on the stem and the cover plate sprang open.
Make sure that the power is off, then remove the cover plate.
Most emergency switches have red cover plates and are clearly marked.
A little spring catch at one end of the box loosened the cover plate.
After you have shut off the power, unscrew the cover plate from the wall.
The cover plate crashed to the deck between them with a bang!
The bottom cover plate has the serial numbers from 1 to 150.
He placed it on its end and opened the cover plate to see that the timer was still working.