[Pendulum^-1]

Polyurethane cord has proven to be useful for making lightweight mechanisms to transport game pieces within a robot.

http://www.mcmaster.com/#59725K704

Typically, 1/4" diameter works well for many applications. You form it into a loop by welding the two ends of a length of cord together, using a small open flame to melt the ends of the cord, then placing them together, aligned, for about a minute. A little tricky, and takes a few tries to get the technique down. Use 4-6 parallel loops of cord strung around/between two spinning PVC pipes, one (or both) driven by a motor to make a conveyor. Some teams use two parallel conveyors, with the game piece between the conveyors, to move the game piece quicker.

Some teams use the flat ribbon form of the polyurethane extrusion, about 1" wide, 1/8" thick.

Recommend getting the cord WITHOUT the polyester cord reinforcement. The unreinforced cord has a few percent of stretch available, which can be useful in making the loop go around the PVC pipes which make the ends of the conveyor.