Find your trash. See what trash is readily available in your local area. Neighborhood recycle bins might be the cleanest potential source. Check also city dumps or electronic waste and recycling centers. Also tell friends and family about what you're planning. For example, Portland, Oregon artist Fujiyo Oe makes handbags out of discarded plastic bags she gets from friends in Portland and Japan.
Know and choose the material. Once you know what you want to make, determine what kind of trash will best support your sculpture. For instance, David de Rothschild formed a team of artists that built a boat -- the Plastiki -- out of plastic bottles pulled from the Pacific Ocean. Aluminum cans, gum wrappers, paper clips, juice cartons -- the potential materials are nearly endless.
Fill a need. Some of the best garbage sculptures meet a demand and even have a functional purpose. Companies such as Resource Revival and Trillium Artisans sell sculptures made from discarded bicycle parts and other thrown-away materials, such as old records turned into clocks.
Send a message. Impressive sculptures also come from a desire to send a notice to the world. Artist Nome Edonna made a sculpture, which she named "Mobile," out of multiple cell phones hung from wires attached to an old bicycle wheel. The sculpture was designed to send a message about the current state of mass consumerism in the world.
Keep it simple. Your garbage sculpture need not be extravagant, such as a giant gorilla fashioned out of junked metal hangers. The book "365 Things to Do Before You Grow Up" lists making a sculpture out of old bottles and cans. And some artists have even taken as-is washers and dryers and made sculptures out of them by painting them artistically. Pablo Picasso even made a "Bull's Head" sculpture by attaching a bicycle's handlebars to a bike seat.