I needed a dimmer knob and plate...
It seems to be a European (UP) standard size. (I had this dimmer http://www.elektroversand-schmidt.de/images/jung_dimmer_266gde.jpg)
Oh, yeah: customizable, just in case.
Edit v1.2 with roundings using my new rounded primitives code.
http://www.thingiverse.com/thing:58478
Also has a rack now.