Idk about that. For some custom built things it might be a better manufacturing method than setting up a production line to cast the piece or forge or whatever. But outside of some really weird screws there are always going to be extremely competitively priced screws of almost every imaginable type. It’s hard to imagine you’re gonna beat that with 3d printing, given you can just buy the screws you need for not much more per pound than the metal its made from.