Present your audience with a box having a transparent lid - show that the box contains nothing. Then, with a single shake, anything you'd like appears inside the box. Very visual. You can use chewing gum, cards, coins, money, change an object's color, and much more ... Perform without worrying about the audience's perspective -- everything is 360 degrees angle-proof.
The box is made of plastic, very nice and durable. You can use it for many other purposes.
Check it out now.