This is a sea turtle shaped cover that will fit a standard single gang US-style light switch. The switch box I designed mine for was sticking out, so there is a bit of a hollow on the back - if you just print it with some basic support, it should work fine on flush switch boxes as well.

If your slicer program offers concentric ironing (I'm using Cura, which does), I highly recommend using it, as it really makes the individual scutes pop!