A good example of technology advancing, I personally remembers submitting a school project when just a child. A boat made of paddle-pop sticks and propelled by a rubber band and a propellor made of bred ties. Oh how i would be the king of the playground with this neat 3d printed race boat.
Zippercraft is a 3D printed, rubber band powered boat. It won the open class Moat Boat Paddle Battle at Maker Faire Bay Area, 2015.
Check out cfishy's complete project at; http://www.instructables.com/id/Rubber-Band-Powered-3D-Printed-Race-Boat/