Heres a link to UHMWPE Ultra High Molecular Weight Polyethylene
Youll find the various descriptions of the shorthand names as you browse the site.

http://www.directplasticsonline.co.uk/home.php?cat=3682http://www.directplasticsonline.co.uk/home.php?cat=3682

Polycarbonate is expensive and Id suggest that youd need perhaps 10mm or thicker.

Heres a link to give you a taste of price ....they dont list the thicker sheet.
http://www.westwardplastics.co.uk/d_selector.php?page=2&cat=glazing&subcat1=Polycarb onate%&subcat2=Clearhttp://www.westwardplastics.co.uk/d_...&subcat2=Clear

(Message edited by woody on October 28, 2007)