The magician shows a penny and a matchbox with no matches inside. These can both be examined. He then places the penny in the box and closes it up. Next he turns it over once, twice, and opens it up. The penny is gone! Everything can be re-examined! Wonderful impromptu routine that will have the specs screaming!
If you keep the penny each time you do this trick you only need to show it 625 times to cover the cost of the tutorial video. Or may be someone will just buy you a beer to learn the secret!
This trick is suitable for all levels.