Hi, I got Carrara 1.1 off a cover disk and I'm astonished. It was immediately useful because I wanted a corrugated iron water tank. I made one by modifying a formula from Jean Pellegri's pages (link found here - merci bien) Here is the formula if anyone wants it. d=4;e=2; p=2*PI*(u-0.5); q=3*(v-0.5); z=e*q; x=d*cos(p)+sin(z*15)*cos(p)/15; y=d*sin(p)+sin(z*15)*sin(p)/15; My question is if anyone has ideas how to put shaders on it. What I want is a very rusty old tank. I would probably shade it globally with a texture map of galvanised iron. The tricky part is the rust which I want to put on only the upper side of the corrugations (or would it be the lower side - now I doubt?). I've been trying to do this with slope from the smart pack but can't work out how to blend the slope effect with a colour or texture. It would also be very irregular and spotty. Any ideas appreciated. George