Houdini Coin Box

You take a coin and ask your friend to mark his initials or his signature on the coin with a marker. You take the coin and seal it in a small  plastic case with rubber bands. 

The plastic case is kept on the table in full view of the spectators.

Now the mirtacle!

You remove a small coin box from your pocket & give it to your friend.
When your friend opens it, he finds another smaller box inside it and opens it to find yet another smaller box. This one has one more small box in it. When he opens the final box, there, he will find, the coin marked by him!
The mini sealed plastic case on the table is now  opened. The coin is not there!

This is the Famous Mysterious Houdini escape ! 

 How?How?? How???

A must-have, best selling trick ideal for your pocket.