http://www.theplasticshop.co.uk/poly...5mm-thick.html
i used the .75, fine for a 1/10 buggy body. have a look in my this year thread for one of the shells. have had polycarb before and its been useless, but their stuff worked reasonably well, needed drying before vacforming though, bubbled up otherwise. if you havent got a vacformer then it might be worth you making your mould for the body and then contacting someone like steve haskins on here to form the body for you