This is the first model I have ever made, I'm very new to this and 3d printing. I used an image generator to get the basic shape. Then I used Tinkercad to smooth it out and add the holes plus the cut out on the back. I made the bottom hole a little oblong because I noticed a little difference in screw placement on other switches. It fits the standard US light switches in my home. 

I printed it on a K1C

using orca slicer

Flat side down, thats the front.

10% infill

See photos for scale, I did have to adjust it to fit my light switch.