Bnjmn™ Gaulon (yes - that's how he spelled his name), Géraud de Bizien, and Karl Klomp of art group De Ponk made this ink jet printer from a paintball gun.
Checkout Printball Printer's cool writeup in Wired:
Straying away from spray cans and markers, De Ponk throws up graffiti with a paintball rifle modded into a point-and-shoot brush. The gun is mounted on a pan-and-tilt unit that's controlled remotely by a laptop. Software analyzes a digital image and creates a set of coordinates that the device uses to aim and fire ink bullets at three shots per second, essentially turning the paintball gun into a large-scale inkjet printer. De Ponk named the machine PrintBall. Its designs - words, smiley faces, shapes - are primitive. But the co-op hopes to try four-color printing using cyan, yellow, magenta, and black pellets, and eventually wants to take its graffiti bot to the streets.