"A trip to the 4th dimension right in front of your spectators" 
Black holes have the property of absorbing everything that comes in contact with them. Some say that they are doors in time and space that allow passage from one place to another. 
During your close-up routine and after some card tricks with the deck, suggest that you'll try something with the case. 
The cards will not be used in this effect - you leave them aside. 
With the case closed, you take a small black disk from your pocket - a disk about the size of a 2 euro coin. "Here's a black hole," you explain. "Black holes are secret doors between the real world and the 4th dimension. Even though it seems ordinary, this black hole allows passage to another dimension, to another place. It allows matter to pass through matter." 
Your spectators will be intrigued. 
"You doubt it? Watch...!" 
You place mysterious black hole on the case. You invite your spectators to watch what happens next... they're not going to believe it! 
Your index finger approaches the black hole. As soon as it touches the hole, it seems to pass into another dimension! 
Yes! Your finger sinks in as if absorbed by the black hole! 
Everything happens within inches of your spectators! You've got to see it to believe it! 
You pull your finger out and repeat at will! 
After a few seconds, you suggest something even more incredible! 
You invite a spectator to lend you a coin. The spectator signs the coin to avoid all suspicion of any possible switch. 
Holding it at the tips your thumb and forefinger, you bring the coin toward the black hole. 
As before with your finger, the coin seems to be absorbed by the black hole - an uncanny illusion! 
Again, the coin seems sucked into the black hole! You let it go and it disappears completely! Seeing is believing! 
You explain that the coin has passed into another dimension, another world. 
You shake the case; something rattles inside! 
You gently open the case and allow the contents to fall on your spectator's palm. 
A coin! The very coin the spectator signed! 
Remove the black hole from the case. There's NO SIGN of ANY opening! Has the passage of matter through matter now become possible? 
Allow me a few more words about this incredible experiment:

• EVERYTHING happens just as described!
• The trick is a marvel of construction, as you will see. Everything is 100% automatic!
• Your finger or even a SPECTATOR'S finger seems completely absorbed! It's crazy, but TRUE! You've got to try it!
• The signed coin is really found inside the case, no doubt about it.
• Before and after the experiment, the case is shown on all sides. There is NO visible hole!
• The feeling of passing matter through matter is UNIQUE to this effect!
• You will fool yourself, so deceptive is the illusion!