Here's a little funny trick that you might know from your first magic-set - now made in a high-quality wooden version. 

You show a small square with an arrow carved in the wood. You flip the square and show that the arrow on the other side points in the same direction. You blow on the plate and when you turn it, the arrow on the other side points in the opposite direction. 

You can repeat this as many times as you want, and you can let your spectators inspect it at any time. The arrows on both sides are completely stuck.

Completely self-acting little optical illusion that seems confusing and mysterious - even when you do it yourself. Comes complete with simple instruction.