You display a solid cube with two holes drilled through the center. You then thread a bolt into the cube, and secure it with the nut. A steel ball is placed in the large hole, on top of the bolt. But it's path is blocked by the bolt. You concentrate and slowly, the ball passes through the cube....penetrating the bolt!
Everything can be immediately passed out for inspection. Only one ball is used and you can repeat the effect immediately.
Imagine bringing this to the office! Carry in your pocket, do ANYTIME. Nut & Bolt are heavy, solid brass construction. Ball is nicely chrome plated.