Love air hockey, but find the tabletop version a little confining? How about busting out the concept of a fan-powered hockey puck into a full-sized version? Here's how to make your own.
1. Cut a hole in a smoke-detector case. Make sure the hole is large enough to mount the propeller and motor from a remote-controlled plane or helicopter.
2. To protect the entire outer surface of the smoke detector, cover it completely except for the bottom rim with a coat of Plasti Dip.
3. Mount the propeller and motor in the hole with hot glue so the air is sucked through the vents of the detector and pushed toward the floor.
4. Solder six AAA cells in series using nickel tabs. Glue the cells in a round piece of plastic with ventilation holes, making sure the weight is evenly distributed.
5. Wire the motor, an on-off switch and the battery together, and attach the cap to the smaller end of the smoke detector. Place the larger end on the floor.
More details over at Instructables.
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.