Always ready; change a penny to a dime visibly.
This is a great simple to execute effect where a US penny changes visibly into a US dime (or miniature penny-supplied). Place the penny on the back of your hand or a spectator's palm and tap with your Sharpie and the penny visibly changes into a real dime.
You can also do a penetration effect where the penny passes through your hand. Many ideas will present themselves.
Always ready to perform. You are supplied with everyhting except the dime, plus detailed instructions. Don't let the low price scare you; it's winner.