Firearm cartridge brass can make a very good puch. Collect brass to punch the i.d. from 32 caliber to the larger diamater 50 and greater calibers for the o.d. punch. Ream and chamfer the brass to a sharp edge with an inexpensive tool for that purpose and readily available from any reloading supplier. Works well.
I have often used old casings for this when I don't find anything better. However I find them way to soft to be really good. (Depends on the material beening punched, of course.) CC
FWIW there are a number of calibers being made with steel cases that might be useable. They might be able to be hardened after sharpening.
