The Solar Marble Machine is a scaled down a marble maze that operates on its own using tiny solar panel. It even works with indoor light, so this miniature machine makes a great desk accessory! The marble tumbles down the funnel, through the chute, and is automatically brought back up to the top to start the process over again. The full circuit takes a few minutes, but it you’re impatient you can speed up the process by using the hand crank. $39.95 for the kit, $69.96 fully assembled!