Place a large bank in an accessible area in your church or youth room. Make up a sign that states what you are raising money for, and the instructions to drop off those unwanted pennies that everyone has too many of. This is a great inexpensive way to raise funds for an event.
Ed. Note – Maybe make a crazy “machine” (like the game “Mouse Trap”) that the coins will drop and roll through before they get into the jar/container to interest the kids and keep everyone giving.