I bought a new Philips hue v2 switch and wanted to mount it over my light switch. This is designed for a typical UK single switch with 60mm screw spacing. I am releasing this as a WIP until there's enough feedback to confirm it's compatible with most switches found in UK homes.

You will need to detach the small metal piece from the holder that comes with the switch, then glue to the back of the print in the locating recess. Only other thing is to get some longer machine screws as it's unlikely the existing ones will be long enough. They're typically 25mm so 30mm should work well.

The 3mf uses PLA with a PETG interface layer for support in order to get a nice finish. You could print it flipped but you'll use more support material that way. Final thing to note. The 3mf shows a dark filament for PETG, I have done this and set the flush very hight to ensure none of the other material is left following the switch. I would suggest you try to use similar or the same colour filaments.

The hole is an M3. I have added a single layer to bridge the hole so it doesn't need supports there. Just run a 3mm drill bit through the holes.