You borrow a finger ring from a spectator and offer to polish it, as you have just received a smart "ring-polishing machine". You drop the ring into the device and start turning the handle on the side, resulting in a loud crunching sound... You look down and by the look on your face, everyone can tell that something has gone terribly wrong. You sprinkle some gold dust on a piece of paper, wrap it up and give it to the owner of the ring, while you say thank you for the loan, and casually ask if another spectator wants to lend you a ring... After this, there are several options:

As the owner of the finger ring is not completely happy, so you put the paper package on a needle, light the paper on fire, and in a flash the ring appears on the stick! Alternatively, the ring can be found in a completely different place... have a look below for more suggestions.

This new Ring Grinder is finely crafted by Arsene Lupin in Poland. It makes a loud sound when the handle is turned and there is a small smart feature built in, so you can choose on the spot whether to pour gold or silver dust out of it,as you never know which ring you will borrow.