The way this works is by wedging your metal ingot in between two halves of a complete die and hammering it until it takes the desired shape.
This kind of thing would be iron-tier. It would cost lots of iron to make these dies and you would need an iron helve hammer to use them. The benefit would be not having to deal with the hassle of manually forging your iron or steel tools with a regular hammer, instead relying on your helve hammer to get the general shape, and then removing the "flash", which is extra material that gets squeezed out the sides of the die, with an iron chisel in the crafting grid.