Your question is a little imperfect. Let me put it briefly:

If you want to use iron (steel) as a mold, you can do it completely. Many molds are made of iron (steel), such as die-casting molds, plastic molds and hardware molds. Their products are made of plastic, zinc alloy, aluminum alloy, copper and iron.

It's okay if you come up with iron products. But unlike aluminum die casting dies, few dies can bear the melting point of iron. But you can use the method of turning sand. For example, there are precision casting molds. The material of the mold is generally aluminum alloy or iron (steel). First, the cast product is wax, and then silica gel, sand and so on are sprayed on the wax. Melt the wax after molding. The melted part becomes a cavity. Hot metal can be injected, and the outer layer breaks after solidification to make iron products. Copper or stainless steel products can also be produced in the same way.

I hope my answer can help you!