Ok I checked this stuff out today while I was at Home Depot. I seen the Polycarbonate material, and yes it was much more expensive. It also seemed to have a blue or green tint. What I bought was acrylic plastic (clear). It's 1/8" thick, but they also sell it in 1/4". You can buy small squares as opposed to a sheet as well. I bought about a 12"x16" sheet. I did a quick test with my Minimag shining in from one edge, and it lit up the border fairly well. I think it will look much nicer with an embedded LED. I want to work this into the Fuzz Face build I'm currently working on.
If this rain ever stops I may just be able to finish the paint job, and subsequently the wiring to the jacks and pots.
Do you sand the edge of the plexi with fine steel wool or anything? Or just leave it as is? How does filing the edge of the plexi affect the light?