few examples of PVC light stands on the Internet. I wanted however for only 3 points to touch the ground (thinking this will be most stable for a given amount of materials used) so decided to go with a C-stand design made of 3/4" schedule 40 PVC pipes and joints.
I am pleased with the result. As one might have expected the stand is not rigid (because of the flexibility of the PVC pipe) yet surprisingly stable. Besides, because of the different height of the legs one can put two such stands very close to each other - try that with alternative designs!