Good match for space fabrication, too. Zero-g makes it much easier for an air nozzle to dislodge debris. Feed it big ingots of metal straight from the asteroid smelters. Not sure if you could do the milling in a vacuum, but it would be worth a shot. Downside, greatly limits cooling. Upside, easier recovery/purification/recycling of shavings. A big electrostatic charge on the ingot and tools should make the shavings literally fly off of the work to a collection plate.
Unless you are trying to obliquely refer to casting, which should be pretty much identical with or without gravity/air. And still needs tooling to make the molds.
(And please don't say that the molten metal could be a feedstock for a printer. That would be a circular discussion.)
Not saying it would necessarily be cost-effective, but it's an interesting idea.
I guess you meant something more like blacksmithing. Chamber could add heat by microwave induction. No air to oxidize the surface so you might be able to work trickier metals. We already have power hammers, we already have 6DOF manipulation tables. I'm not entirely convinced that a power hammer could do the work accurately enough, might want to use a milling machine for the final fitting.