Here's one for you;
How many out there use a clamped ruler and an X-Acto knife( drawn Backwards and upside down) to make a cut and then re-cut, then release the clamps and snap the plastic to get what you want?
Well I just purchased this cutter at H.L. It's to be found in both the art department and sometimes where the stained glass is because that is where the thin sheet Plexi is at. Clamp, Slide the cutter once with gentle pressure, release clamps and snap. You've got your piece
This works well on the heavier thicker pieces and is awesome on the thinner ones, Plus you can now cut and score your plexi and make your own cases.