Hollow PVC pipes make a sound when you hit them with something. The longer the PVC pipe, the lower the tone. Using different PVC pipes of various sizes, you can make a simple xylophone. Experiment with different lengths and thicknesses of PVC and try hitting them with different objects to vary the tones.
Cut several different lengths of PVC pipe with a fine-tooth saw. Start with a 6-inch pipe and work up to 18 inches or so.
Line the pipes up side-by-side, from shortest to longest.
Tape the pipes together with two strips of duct tape. Wrap each strip around the pipes at least once to create a thick layer.
Make drumsticks out of dowel rods or more PVC pipe. Cut two 14-inch long sticks and wrap one end of each in duct tape to form a ball.
Lay the PVC xylophone on the ground and hit it with the round ends of the sticks. The different-length pipes will make different tones.
To make your PVC instrument sound more harmonius, try making the lengths of all your pipes a multiple of the first pipe. For example, if the first pipe is 6 inches long, make the next one 12 inches, the third 18 inches and so on.