Heavy Metal trick Sam Woodrow
A bolt and nut with a washer threaded in the middle are handed out for close examination. The assembled hardware is dropped inside a paper bag and the magician claims that with "just a few shakes of the bag" he can loosen the nut, slip off the washer, then actually screw the nut back onto the bolt! He then does precisely that, and everything can be once again examined, including the bag!
Heavy Metal comes complete with the specially machined hardware, paper bag and illustrated instructions with a full professional presentation."