The best way to cut a straight edge on Plexiglas is with a circular saw. A circular saw is ideal because it can cut through multiple ranges of thickness. Scoring Plexiglas to prevent scratching is also recommended.
If the masking is still on the Plexiglas, it should be kept in place because the masking helps the saw glide more easily through the Plexiglas and also protects the surface of the Plexiglas from flying debris. The edge to be cut should be measured and marked carefully and then scored with a Plexiglas knife. The scoring prevents uneven edges and breakages as well as scratching. Once the edge is scored, it can be easily followed with a circular saw. The saw should have sufficient horse power to not stall or break on the material. For a circular saw to work properly, the blade should also have at least two inches of clearance from the top edge of the Plexiglas. Proper safety gear should always be used when operating a saw. Other saws can be used for thin, lightweight Plexiglas but are not ideal for cutting thicker sheets. Scroll or band saws should only be used for adding special design edges after the Plexiglas is initially cut to size.