I had to get some plastic windshield after I mess the one up that came with the kit. I got it from this outfit and it had the blue paper between the sheets. None of it was scratched or damaged in any way. They had lots of differnt thickness and different sized sheets. Sure couldn't complain about the price either!

http://www.happyhobby.com/hobb_html/sig.htm

Go to Sig, Then look up clear plastic sheets. They are in the same general area and give all sizes. Part number 1438057410 is the area where you want to be looking.