So far I’ve turned stainless steel, mild steel, aluminum, delrin (a plastic), brass and today it was rubber. Rubber is interesting to turn. The main thing it requires is very sharp tooling. In this case I ground a cut off tool real narrow. I then ground and honed the top and front edges.

The tooling requires a certain amount of rigidity. For example and razor blade won’t work.  Because the rubber flexes a great deal, I’m using the live center to support the end of the piece.