This is a suggestion for another link in the industrial manufacturing process.
I would like to see forges and crucibles added!
At the moment, once you have some bars of metal, you can make them into anything you want by way of an anvil and a hammer. It seems to me that there is space here to add another important step, heating up those bars so that they can be shaped, or melting them entirely so that they can be poured into crucibles.
An anvil, for example, could be made by melting down the required bars to liquid form, making an anvil shaped crucible out of clay, and then pouring it.
Of course, the process is alegorical. We don't want to mimick everything in real life down to the smallest detail, or it would just get too finicky and annoying. However, I think this is one process that should be added!