Matthew Davis' Arcus is officially the most impressive thing we've ever seen come out of a 3D printer. Sure, cheap prosthetics and replacement body parts are important uses of the technology, but this spinning rubber band blaster is what finally makes us want to put a 3D printer on our desks.
Unlike most rubber band blasters that only fire a single shot every time you squeeze the trigger or require a drive mechanism to make them fully automatic, Davis' Arcus uses the energy from the loaded elastics to spin the barrel and automatically fire shot after shot until it's empty. Brilliant.
Over on Instrucables, he's posted links to all of the 3D models so you can print your own as well as a break down of how the Arcus works and instructions on how to assemble the myriad of pieces your 3D printer will be churning out.
Just make sure to stock up on rubber bands because you'll be quickly losing them once you start playing with this thing.