The 10p Go Box (Teak)

This is a practically hands-off effect in which you can use a borrowed signed 10p coin. Have your spectator place their cownin the box, and lock the box. After you make sure the box is secure, hand it back and ask your spectator to check again to make sure the ring is inside.

To their surprise, the box is empty and the 10p coinis discovered inside your pocket.