The Trapdoor by Steve Beam Issue 1, 1983 Page 6 et seq.
Personal Comment: Practical! But personal. I can see this being a pet routine of Steve Beam. And I see why lot's of magicians seem to have requested to see this one during conventions as Steve claims in the Issue. SO I won't use it... but everyone can make up his own version. With as many "displays" as one likes.