Re: Lexan/polycarbonate vs acrylic
Plexiglass (R) brand of acrylic glazing is just one brand. There are probably 20 or 30 different grades of clear Plexiglass alone, and most of the other brands will also have at least two dozen different grades of clear acrylics. Less variety in the tinted colors.
So you need to decide, local or mail order. Then find out which brand they carry, most shops only carry one or two lines.
Then you figure out which grade of the product you want, from what they have available.
In a choice of cast or extruded, some will say you only want extruded but that's going to limit your selection again.