I prototyped Illuminatrix on my printer Cupcake155. Then I built the DeltaFlyer and recently got around to installing Illuminatrix. The original setup uses a full Arduino Diecimila. It's physically big and I decided to reduce some stuff on my second round with it.
Here it is in its second iteration:
Here I'm using an Arduino Mini Pro instead of the full Diecimila. Controlling it is different since there's no FTDI and thus we have to use legitimate RS-232, but all I actually had to do was connect the Mini Pro's RXD pin to the Raspberry Pi's GPIO TXD pin. This course depended on first having actually flashed the Mini Pro with my Illuminatrix Arduino firmware.
Since I build my printers around ATX PSUs, I have 5V and 12V rails handy and that helps a lot for Illuminatrix. As you can see above, 5V from the PSU goes right to my board. I run the 12V line to my Vcc of my LED strip and that's it for power (plus GNDs, obviously).
I'm toying seriously with the idea of doing a PCB run to formalize this, I am very much not happy with wires hanging around, so I think there's a good chance I'll make this clean. In that event, I may order a bunch of extras and possibly make them available as kits. Please please drop me a line if that interests you, I wouldn't really be doing this to make money (I'm highly employed as it is).