Uses a small battery powered led light with a magnetic switch mechanism.

They're about . 3mm thick and flex like card stock. I can fit 3 to a plate, with the plate taking about 7 hours to print (I likely could have cut this down a bit by messing w the file, but after much time playing with the settings, I was happy with this quality and didn't want to fuck with it any further since time is on our side). Each invite is about 10gs of filament including waste.