At that time, we sent them an Arduino kit and the project was intended to be completed with anything they could find around the house (cardboard, foam board, etc). Some had 3D printers and made better solutions, but that wasn't necessary to get full points. Lot of them went and bought red/blue poker chips to use as the "coin". The best one had a hopper that fed them into a chute. Had a servo that stopped them at a color sensor, then tipped a platform below that in the right directions to that when they let them pass, they either fell into the left bin or the right bin. He got through about 300 poker chips in 3 minutes.