Homemade musical instruments don't have the appearance or range of commercially made instruments, but they provide a sense of fun and can make music in their own right. You can make a plastic tuba using the wide mouth of a plastic water bottle to produce a deep sound similar to that of one used in orchestras. Some household supplies and tools will be needed, and the body for your plastic tuba can be acquired from a home-and-garden-store.
Place a sheet of newspaper on a work surface. Place the empty one-gallon plastic water bottle on the newspaper. Measure up an inch from its bottom with a ruler. Draw a circle around the bottle at the 1-inch mark with a grease pencil or pencil. Score through the outline drawn with the utility knife. Continue scoring through the outline until the plastic is cut all the way through. Remove the bottom of the bottle.
Place a plastic drinking cup face down on the newspaper. Cut a 1-inch diameter hole in the top center of the cup with a utility knife. Measure 2 inches down from the top. Draw a circle around the cup at the 1-inch mark. Score through the outline with the utility knife until it cuts all the way through the plastic. Pull the cut bottom off the cup and dispose of it.
Place the cup face up on the newspaper. Apply bonding glue around the hole. Place an end of the rubber tube into the hole. Hold the tube in place for a minute so that the glue can take hold. Let the glue set overnight.
Turn the cup over. Apply bonding glue to the top of the cup. Place the free end of the tube into the hole at the top of the water bottle. Place the cup over the neck of the water bottle. Press the cup against the neck so that the glue can take hold. Let the glue set overnight.
Hold your plastic tuba so that the cup which is now the mouthpiece is facing you and the wide end of the bottle is facing away from you. Place your lips against the hole in the cup. Exhale noisily into the hole to drive sound out from the tube so that it can resonate inside the walls of the water bottle. Vary the humming and strength of your breath to continue to make sounds come out from the open end of the bottle.