Jeezum crow! This guy has made a fully functional (kind of) Proton Pack from Ghostbusters including a trap, ecto goggles, and some coveralls. He added a few lights controlled by an Arduino board.
The best part? He added lasers to the blasters. Now he just needs to remember not to cross the beams and that your halloween party can be a promotional expense so you should invite clients instead of friends.
The instructions are, obviously, at Instructables.