Thanks guys
A cast iron pan is about 3 mm thick. I don't know whether that's thick enough.
That would be OK. But I am worried about anything cast iron, it may be too fragile to take hammer pounding. I don't know.
Besides, most of these are too big.
Another idea is to check with any local metal shops in your area for a chunk of "scrap" they may have
Good idea. I will try it.
They will definitely have all kinds of bits and pieces of metal around them.