Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:4778182.

I bought Wyze Thermostats, but found that they were created for vertical mounting. This makes them not usable with older Honeywell horizontal thermostat mounting. While you could just create new holes and such, I decided to make my own to use the existing mounting screw locations, and cover (mostly) the old thermostat's footprint. Didn't quite cover the paint gaps left by my old thermostats, but this worked out well enough.

I created this in two parts, so that the base could be screwed to the wall, and the cover hides the screws underneath.

I've included the Fusion360 file in case anyone wants to edit it to fit their particular situation.