Look around your garage for random metal objects, most of the time you'll find something that can be used, even if slight modification is needed. It can be hard sometimes, but you should be able to find something.

One thing I was using up untill recently was a bong made from a mountain dew can, two of them really. I cut up one of them and shaped a bowl out of the aluminum can, just sorta made a funnel-shaped bowl. Worked really good for the most part, main problem is I only used ductape to secure it, and after smoking it the flame would heat it up and sometimes the bowl came loose. So make sure you secure it well.