I have worked with a friend for many years to make fiberglass "skin" lay-ups that use RenShape 440 material that was machined by a contract company with a large ShopBot CNC router. When I home-built my two CNC machines after retiring, I cut some some molds for some of his R/C models, wind tunnel models for commercial and military projects, and UAV/RPV projects. It does carve well, and when finished properly, can make very accurate surfaces for the lay-ups. I still help him out some when he gets behind on a project. Some of the wing panels are 10 feet long and require some heavy lifting to move the molds around in his shop. Fun work though.