Extreme forging machine on an epic scale. These forging machines melt and craft raw metals into a more workable product for later manufacturing.  
Seriously, smithing over the centuries is really a mind fuck as to how humans have learned how to create alloys and then shape them to whatever they want!
I've always wanted to know how ball bearings were made!  Surprised they didn't talk about induction. I have a client they run their rods through an electrical current, heats them up for pressing in a matter of seconds (also Germany also is known for making custom machines themselves for clients, I know of one, there are only 2 of the presses in the world).
For the record that first step, gears can be done that way too (if there's a mold).
(Actually surprised of my clients didn't show up in this ... then again it seemed like 1/2 were specific companies, and 1/2 were processes)