You mean the 2x4 plastic panels you find in office lighting environments? I would think "no way!" can these be used. They're not very strong, brittle even (depends on what type of course) but to my knowledge also they wouldn't hold-up under direct sunlight; they'd likely discolor or worse, self-destruct.

oh, thanks for the input laserfan. It was one of those ideas you get while lying in bed, avoiding geting up. :-)