I am trying to create a sheet of rusty corrugated iron for a backdrop for a piece I am creating. I have had no luck with the formula object. I tried x=u; y=v; z=sin(u); This does not create a wavy sheet?? I've had a little luck with a squashed rectangle and the linear wave modifier but the performance for screen refresh is terrible (PIII 400Mhz 512Mb). When adding a rust shader the performance of the render is dreadfull Any recommendations? Regards, Andy Clark