I scrounged some 1/4" polycarbonate lexan for windows, and I thought you might like to see a safe way to cut it. The waxed Asian style saw (Vaughan Bear Saw BS250D) cuts it very cleanly and straight, and a handplane will clean it up further. The 66" cut took about 15-20 minutes. I definitely recommend these saws for all kinds of work. They're efficient and give a high quality cut.
Here's the setup: The lexan was placed on two 2x12 planks spaced with a 1/2" gap to saw through. A candle or paste wax lubricated the blade. It was not difficult to split the pencil line.

Here's the sawn edge. You can see that the saw was drawn through the material at a shallow angle of ~25 degrees. This eases the sawing and helps keep the cut straight.

After shooting it with the handplane, the edge looks like it was done with a jointer or router.
