There are very nice commercially produced tripods available, including expensive wrought-iron ones. This one can be made for $20-$25 if you buy everything brand new, and will be nearly as durable, and certainly lighter. It could be made cheaper, even free if you can scavenge the parts from scrap. (Update - I just saw a wrought-iron one at Joe's sporting goods for $45. I think I'll stick with my conduit one.)
Credit for this concept goes to Junior Doughty of www.deltablues.net. His tripod can be found at: http://www.deltablues.net/tripod.html
Step 1: Materials and tools
3 sections of 1/2" conduit 4' long or longer
3 sturdy eye bolts
4' of chain - the kind with the wire links is great.
Tubing cutter or hacksaw
Step 2: Cut the legs
The tubing cutter has little rollers and a cutting wheel on a clamp. Tighten the clamp onto the conduit where you want the cut then tighten it down, turn, and repeat until the conduit is cut all the way through.
A hacksaw may also be used to do the job.
If you don't have a way to cut the conduit, the hardware store may cut it for you when you buy it.