Plexi Glass.

[ezdays]

To start with, you need to sand it as smooth as you can, use progressively finer grit until the score marks and any saw marks are out. Then you can use a torch to "flame polish" the edges. Just run the flame back and forth, not stopping in any one place and you'll see where the edge surface melts just a bit to give you your polished edge. Keep it on too long and you wind up with toast. The smoother it is to start with, the quicker it will polish.

If you don't want to try that, you need to polish it with a buffing wheel, but the same thing can happen, you can melt or burn the edges if you're not careful.