Only 1 Pen is Used
You borrow a bill from a spectator & hand them a pen to make a mark on the bill.
Now take the signed bill and stab a pen right through the bill!
You then move the pen and hole to a different spot on the bill!!
Pull the pen out of the hole, but where is the hole? You give the bill back to the spectator.
Locking Pen with Box!!!
Very easy to do.