so the performer instantly knows which force is inside

The magician may shake the box to make sure the coin or ring is inside which is confirmed by a rattle sound

The title really reflects the contents perfectly

Here's a great card clip

then you'll need it to be PORTABLE

Stretcher | Jay Sankey Will so the performer instantly knowsShocking magic with a BORROWED item! Easy to do + extremely visual! Works with any tab from a can of soda or beer! Effect : The magician asks someone to snap off the tab from a can of soda or beer. The performer then holds the borrowed tab at the tips of his fingers and slowly, impossibly, STRETCHES the tab to an insane length! The impossibly stretched tab can even be closely examined! To finish, the stretched tab is visually shrunk back down to its