I have an entire slew of didgeridoos! Some are made from PVC; that's both plumbing and electric conduit. There are also a few made from bamboo, cardboard and plastic tubing (not limited to PVC).
Here are several sample sounds. I've tried to keep each file small, for easy download. That's small: 150 to about 800 KB, on average. One may be about 1.5 MB
This one's made from flexible tubing.
A three-foot PVC didge
The real thing (authentic didgeridoo)
A bamboo didgeridoo
A cardboard didge (mailing tubes or three paper towel rolls)
Five foot long PVC didge
This one's made with vacuum cleaner hose!
This one's the longest--about seven feet!
Here's another bamboo didge!
Here's a PVC didge bent with a heat gun!
Here's another PVC didge with curves and angles!
Here's a five-foot long PVC didge curved with a heat gun!
I hope this gives you some idea of the variety of materials you can use to make didgeridoos. Each of these instruments is made with beeswax mouthpieces, in keeping with what I figure to be Australian Aboriginal tradition. I've also found it useful to woodburn designs onto my bamboo didgeridoos and paint the PVC ones. Acrylic paints seem to work best with the latter. Acrylics don't smell too bad and are easy to clean up. Also, I've used a heat gun to bend pieces of PVC so the instruments resemble those of the authentic variety (typically made from Eucalyptus branches). Proper ventilation and a considerable amount of caution are required for the use of a heat gun. You can visit my site on geocities for more information. Please feel free to check out the links as well.