I totally missed this on DIYPhotography.net until Alim Kassim clued me via Twitter.
A little bit of quick and easy DIY (and ball bungees!) turns an old film camera into a focusing strobe projector. You can actually buy these things for some models of big lights, but they will cost you some serious coin.
I'd probably use one differently than did the photog on DIYP. Like maybe painting numbers or something three-dimensionally onto someone's face or something. Great idea to keep in the back pocket, tho.
If it looks familiar, it is a simplified version of the "Image Fulgurator" created by photographer Julius von Bismark. But he used his for public mischief...