Magician passes for inspection a solid brass block of metal with a hole in its center, along with a steel ball, and a brass nut and bolt. The hole in the block of metal is large enough for the steel ball to pass through.
Now the bolt is pushed through another hole in the block and locked on with the nut thus blocking the passage of the steel ball through the large hole. Anyone can try but no one can push the ball through the bolt.
Amazingly, with one pass of the magician’s hand, the ball melts completely through the solid bolt and comes out the other side!
Everything can be examined.
They won’t believe their eyes!