Chaos lightswitch plate

This thing was inspired by https://www.thingiverse.com/thing:1265775, but I couldn't make that one work for an American switch—the backplate was too small to cover the switch box, the holes aren't lined up, and the domed backing (from https://www.thingiverse.com/thing:168418) printed in visually unappealing concentric steps.

So I built this from scratch. I've tried it in a couple of places, and it seems to install tidily. The hollow backing does require supports (without the hollow it doesn't sit flush to the wall), but they came out quite cleanly for me.