I based this one on the gun in Predator, kinda. Too small, too little detail but it WORKED. Non-firing, but the barrels spun at a good 900rpm with a fresh drill battery attached. I went on to build literally hundreds of these crazy costume Gatling gun. The barrels are 1/2" conduit, the body cut from 6mm thick ABS plastic from Interstate Plastics in Sacramento.
YOU can build a much nicer one, get the CAD files for this Minigun Gatling Dummy at www.mrminigun.com