Thanks all for the encouraging replies. I think i'm going to move ahead and give this a try on the full scale!
To elaborate on why i REALLY want this to work, just let me say that in a single afternoon, I was able to try 12 different methods (various shapes, sizes, ways of cutting, heating, molding, etc) in one foot sections. Compare that with other methods of making blades: It would take weeks to try 12 different options. So clearly, if this works, it could help a lot of DIYers get in on the fun. More people trying different shapes, sizes, and methods means faster innovation and improvements that we can all adopt.
I hope it works out, and, if so, I'll post pics etc. But to quickly break down what i'm doing here's the super simple overview.
1) cut a line down the length of the pipe
2) heat that sucker to about 350-400 degrees F
3) flatten it into a board. place between two pieces of plywood and stand on it for a while
4) now you have a 10'X14"x.25" thin PVC board (assuming you started with 4.5" schedule 40 pipe). you're going to be surprised by how sturdy the board is.
5) set the table saw to 8 degrees and taper both edges
6) heat the board again, this time targeting only half of the width (i set wet wood on the half i want to stay cooler)
7) carefully wrap the heated (flexible) end around a wooden "frame" (basically, strategically placed thin strips of wood)