Contraption Lab

Fifteen boards, one ball, and a dock full of parts. Drop a ramp here, a fan there, power up a conveyor belt, and hit Go — then watch whether the machine you built actually does what you thought it would.

Parts

• Ramp — gets things rolling.
• Fan — a steady push through the air.
• Seesaw — land on one end, launch off the other.
• Balloon — floats up against its tether.
• Conveyor belt — inert until the ball hits its motor.
• Rocket launcher — one enormous shove.

Every level has a par: solve it in that many parts for three stars. Most can be solved messily on the first go and elegantly on the third.