A box 11" x 4", having two doors and a space between them, is shown to the audience.
A large coin, 2 1/2" is produced from your pocket and placed into the box.
The box is tilted and the coin vanishes from the side where the coin was placed.
Only that door is opened.
The audience actually sees the coin travel from one side to the other.

This is repeated over and over again while the audience shouts that the coin is on the other side. Finally both doors are open.
The coin actually has vanished and is produced from your pocket.
No sleights! All mechanical!