build a compass

Paper Cones:

Cardboard Derby

Electroscope

Sailboat, toy-sized

Sailboat, Full-size

Boomerang

Ping Pong Levitator

David Hamel's Anti-Gravity Generator

Nicola Tesla's Earthquake Machine

Kayak

Supersoaker

Gunner's quadrant

Circumferentor

Theodolite

Electric Car: Toy and gokart

Pinhole Camera

Camera Obsura