Andrew, Great image! Even if it is not logical when you examine it, it still helps to bring out the geometry in subtle and convincing ways. I've got some military surplus hardware lying around that needs a shader like this. Would you mind sharing your formula? That olive drab is convincing. Yeah I see it as a 2-part dirt'n'damage shader. One shader to detect inner grooves, the other to effect outer edges, and some sort of fractal noise to define the scale and randomness of the damage.... Eric has LOTS of work to do! He'll probably regret me ever posting this WireframePro trick! har har har holly