I used to have a Memphis shades screen on an old Honda Shadow that I trimmed by using a jig saw and then sanding down the edges till smooth. The plexiglass was very thick, though, so I didn't have to worry about cracking. To keep the base of the saw from scratching and scuffing the screen as I trimmed, I just put clear packaging tape on the screen all around the trim line. Came out really good. Just be careful and use a finer tooth blade. The plexiglass did have a tendency to try and melt and "ball-up" from the heat that the blade generated. But, that extra "balled up" material was easily sanded off.