Greetings from Nebraska.
I would suppose you would need a feed-through CNC lathe for turning nibs, couplers, finials, and the like. Something like that could also be purposed to slice brass tubes to the appropriate length. The only somewhat cost effective way to make clips and such would be to have a small stamping operation - most likely a 4-slide machine that could not only do some stamping, but also some forming operations. Very few manufacturers do their own in-house plating simply because of the EPA and environmental implications associated with electroplating, they outsource. There are plenty of USA based plating houses that can do decorative chrome, gold, etc. Of course the standard shop support equipment would be needed as well, air compressor, tool sharpeners, surface plates, measuring equipment, pallet jack, small forklift, etc.
I am sure there are other tool and die things that are job specific, but as far as research goes this is what I my starting point would be.
Dave