Yet? You can certainly cut, bend, or machine brass now. Though you may need your own tooling or inserts for machining; all of ours are meant for aluminum and/or steel, and brass uses a different rake angle. I’m not averse to getting some brass specific tooling/inserts though if people want them. I’m not aware of any issue with zinc for those actions either.
The main rule in the metal shop is, that if you are using an unconventional material, you are responsible for understanding any issues with it. It sounds like sanding or grinding brass or zinc might require a bit more care, likely breathing protection for the user. And it seems high heat can generate dangerous fumes from them. We will definitely be upgrading the ventilation of the welding areas; I don’t know yet if that upgrade will handle that situation. I certainly hope we can do that.
There has long been talk of adding a jewelry making area, usually as an adjunct of the electronics area. I don’t know if that’s on the agenda for the second phase re-organization or not. We won’t be able to carve out a separate area for this in the metal shop, but anything you can safely do with the new equipment and ventilation is certainly OK. That probably sharply limits the chemical possibilities, but I’d need to know your exact needs to say more.