oh,,i'm sorry Dag-,, i never thought of that,,i guess it would be hard to hold a helmet still while smacking it with a hammer.
i bought my copper rivets from tandy/ the leather factory,,,i guess saddle makers use them a bunch,,but i'm just guessing.
most of my work is on the back of a sheath holding the belt loop closed and that is flat work,,,
oh,,wait,,a bowling ball,,a bowling ball on a stick then you could whack the snott out of it and not chaise it across the room,,,maybe-maybe.