This is a remix of the model N3RD Solutions posted, so a big thank you to him for making the original.
The original doesn't have a hollow back which can interfere with the hardware making it not flush to the wall.
Double version: https://makerworld.com/en/models/133809#profileId-145201
Triple version: https://makerworld.com/en/models/146168#profileId-159136
The changes made from the original design are the following:
I have added the 3mf file of the project that includes custom-painted supports as well as my model-specific tested support settings that make it relatively easy to take off with the printer clippers. I have also added the variable height function to speed up the print a bit where detail is not needed.
*Disclaimer*
Normal switch covers are typically fire resistant while normal pla is not. You are responsible for your own safety, as am I. The chances of an electrical fire are slim but never zero. Do what you will with that information.