This is a very ignorant comment, as is the one you're replying to. Making engine nozzles used to be extremely manual and involved process, which could take up

This is a very ignorant comment, as is the one you're replying to. Making engine nozzles used to be extremely manual and involved process, which could take up to a year to make a single nozzle. These need very particular channels within the walls for cooling, and that's impossible to manufacture with simple reductive methods. They used to form wax modls and deposit nanometre layers of metal.