Start saving your cat food cans, and get your friends to do the same. Go to the recycling center and grab as many as you can. Using clear packing tape, you can tape the cans together and create long cylinders, out of which you can make innovative and unusual abstract art. Stand them up with one end buried in the ground to create poles, or stack them in solid blocks. The more cans you have, the more creative you can be with this idea. Be sure to clean them well when you save them, or you may have some smelly art on your hands.
Mimic the masters with cheap materials. Most people have bits of house paint left over from renovations that will never be used. Gather up some differently colored house paints and do your best impression of Jackson Pollock. Get pieces of hardboard, plywood or other sheet materials. Even a 4-by-8-foot sheet of drywall will work. Lay it on the floor and do a bit of drip painting. Go to the library and take a look at some of Pollock's work in an art book for inspiration. If you can convince someone that it's an original, it's good for at least 10 million bucks.
Ephemeral art made of matches may be the medium you were made for. Invest in 10 or 20 boxes of wooden kitchen matches. Lay out a piece of newspaper on your kitchen table and get to work. A bit of Elmer's glue, a utility knife and the matches is all you need to get started. Build up structures and forms out of matches by gluing them together. Create walls, towers, organic forms and flammable tree branches. Use the knife to cut the base of a match stick to a 45-degree angle, enabling you to glue them together in a wider variety of ways. Gather some friends together at night, set up your temporary artwork outside, utter a ceremonial prayer and strike a match.