As the saying goes, one man's junk is another man's treasure. With a little effort, time and creativity, anyone can take "junk" and turn it into a musical instrument. If it is able to produce or be a part of something that can produce any sounds, then it can be considered musical. Across the globe, instruments are being made from aluminium cans, discarded paper products, plastic bottles and just about anything else that is available.
Acquire junk if you don't already have some lying around. It should be clean, safe of jagged metal and broken glass. Anything that has qualities of resonance or acoustics can be used, including tubes, flat pieces of wood or metal, or anything that has been discarded and is capable of making an interesting sound.
Sort the junk into piles. Larger sections may be used as starting points and foundations. Smaller scraps should be kept together for joining other pieces. The bulk of the items should be part of a larger vision. For example, imagine that 88 plastic bottles will make a full-size plastic keyboard; paper towel tubes and sand can make noisemakers; or buckets and rods will make a drum set.
Sketch an idea based on the available materials as they have been sorted.
Assemble the parts using duct tape and zip ties for structural integrity, and Scotch tape and masking tape to reinforce joints and create seams. If making an instrument that needs blown air to produce sound, keep in mind these joints need to be smooth on the inside so as to not disrupt the vibrating air.
Play the instrument and record the process. This way, if it breaks, the video will show what was structurally unstable and where it needs to be reinforced. Also, if it plays fine, the video can show where there is too much vibration or where improvements can be made. This is difficult to evaluate rationally when performing and trying to evaluate at the same time. That first musical voyage will be too much fun to concentrate on troubleshooting.
Be careful when handling junk. A cut or scratch from a dirty or potentially bacteria-covered item can cause serious damage. Research the idea. Others may have tried something similar and study can help save time while improving on an existing idea.