Dicey Cubio Cube

By Wonder

A large dice Cube is threaded on a string, and slides freely up and down. Yet whenever the performer wishes, he can make the cube freeze on the string at any spot.  The cube can be handed over for examination, and the spectator will find its slides freely dow the string.  The spectator cannot make it stop on the string.  Only you, with your magical powers, can do so.

Skill Level: Basic