Here you find how to forge a hammer
get iron
put the iron in the forge with tongs
put the hot iron on a flat rock
hit hot iron with a round stone
put the forged iron with charcoal in a bowl
seal the bowl with a plate
get it back in the forge again
now you have steel ingot
put steel ingot into the forge again
put it on the flat rock
hit it with the round rock again
combine the hammer head with a short shaft