Snowball Launchers, Giant-pumpkin Growers and Other Cool Contraptions by Tom Fox
One look at any of these gadgets you can make and your friends will call you a mechanical genius - or a mad scientist! Build a rocket-propelled toy car or a secret place to hide your treasures from snooping little kids. Grow a pumpkin so big, even an adult can't lift it. Make an automatic dog feeder, a mechanical snowball thrower, or some storm-predicting bells. All fifteen "Amazing Stuff" projects produce toys that are more than playthings. Yet all you need are some pieces of wood, nails, oatmeal boxes, jar lids and ice-cream sticks - using just a hammer, screwdriver and other tools from around the house - plus a couple of cheap electric motors you can buy at any electronics store.