When he first posted it, I sent a link to my cousin who is a farrier and actually makes hammers. He had no idea.
One side is inserted into something and twisted to tighten it. Ifmthenitem is recalcitrant it is hammered with the other end. No idea what the item is though
Is it time for give-away hints yet? martin and Kylek the Vulcan are warm enough to be irritated if they don't figure it out.
Hammer for roofing? Installing sheet metal or copper, first, to make holes in the cladding, then hammer in the fasteners?