I stumbled across Li Garone's Victorian Light Switch Cover and thought it was absolutely perfect for my wife's decor aesthetic. Unfortunately,  Li only had a “rocker” switch version, so I went ahead and edited her .stl file for the other most common type of switch. Printed and tested, seems to fit just fine. Please keep in mind that I had to edit this from an .stl file, so if you're familiar, you know that means editing a mesh object…it can be a bit cumbersome, but overall I think it turned out alright! Just in case, I also included the .SLDPRT file, if anyone wants to do it better than I did in Solidworks.

I printed mine in ABS at 100% infill, but it shouldn't matter much.

I added a 3MF of both the solid color version as well as a version with the filigree design in a different color, as seen in my example pics.

Enjoy!