I am using a hydraulic press and reviewing pressings into my steel and bronze dies. I have used urethane,bicycle inner tubes,lead and cardboard. It was mentioned that pewter and zinc can be used. Anyone care to comment. I have pewter which was given to.me that is silvery bright but not sure what hardener has been added to tin. But I will give it a whirl…lead has worked best for me so far…east to re-melt and re-use.