For 30 x 40 I would stay with glass, just me. I only use Plexi as a last resort or when selling to an institution where breakage/liability is an issue like a hospital.
You can order standard Plexi (4 x 8 sheet) and cut it down if you have a wall cutter, other wise, you will need to have it pre-cut. Plexi is eaxy to cut but needs a certain blade.
The only issue you may run into are flaws, (mainly bubbles) that will easily show up when you start to mount. Most plexi will have a few of these especially the lower priced brands. I source from a local plastic shop in my town. They can provide the full price range, top end UV to the lower priced. Most of the stuff I am using is made overseas.
One other note not sure if you have used it before. Plexi has will have a paper cover on both sides and this can be a bit tricky to get off. Easiest way to keep a large roll from one of your larger papers (printer paper). then use this to roll up the paper cover from the Plexi. It will make removal much faster and cleaner. I try to go straight from the paper removal to the print, do not try to clean it as this just adds static and then dust.
Best clean is the Novus set, 1,2 for sure. I would recommend the static free rags sold in Auto Zone store for cleaning if needed.
Paul
