I put three elastic cords over two bottles. By flicking the elastic cords, the cords vibrated and made a sound when they collided with the bottles. At the same time I put a coin in the can and rang the can while the coin inside vibrated and made a sound with the can. Finally, these items are used to play. Just hitting the plastic bottle and the can makes a monotonous sound, and by doing this I can improve the sound and make it more beautiful.