Mechanism for American TV show Top Shot

Grey balls are released one by one to roll down along a railway that consists of several sections connected together in zigzag shape. Each section has a gate (hole) and its cover. The video shows only one section. If the cover is open, the balls fall through the gate. The contestant tries to hit violet round target for closing the gate to let the ball continue rolling in the railway to the final basket at the railway lower end. Winner is who gets most balls in the basket. See the show at: