Draw a circle with a square - Tack two nails to set the diameter you want, then rotate a framing square against the nails while you hold a pencil in the corner of the square. Rub a little wax on the square so it slides easily.
Miniature cars from aluminum cans. After drinking soda from aluminum cans, you can recycle your soda cans to create interesting projects instead of tossing the empty cans into the garbage or recycling bin.
Craft Stick Catapult - my awesome Cub Scout companion leader used this to teach Leave No Trace: need 7 sticks for outdoor code rules, and signature. Band 5 of the sticks, band 2 of the sticks. You rock, Kimberly P.