OK Mouse,
The glass man happened to be at work tonight when I arrived. With your question on my mind, I asked him how he cuts lexan/plexiglass. He uses a cordless circular saw with a fine tooth blade, like a plywood blade, then he dresses the edge up with a file. Bear in mind that he is cutting windows that sit in rubber mouldings, so the smoothness of the edge is not a big priority for him. I asked him about trimming down a bike windshield and he said you can buy a knife at Lowes or Home Depot, like a carpet knife, and with a layer of tape and a straightedge, score it some 30 times or more and then snap the piece off. But you will never get a clear, rounded edge at the point of the cut. You can sand it smooth, but it will always have that rough hacked look to it...
