Speaking as someone who, at least as a sideline, does machining stuff in a home shop, I have to wonder about some assumptions. At least as far as scale is concerned.
There's obviously going to be some groups making Stuff, Up Here. I wouldn't leave home without my mill and lathe and such, and I know there's a bunch who'd feel similarly. I have no doubt that there's going to be some quasi-Makerspace setups too that are open for use, but I also imagine they'll be pretty heavily booked up. And anyone who's making the effort to loft machine tools for their own use is going to be utilizing them pretty heavily. I mean, a basicish CNC mill starts at around 20 grand or broadly equivalent in time to convert a manual mill, plus it's about a ton or several of mass that has to be moved, plus infrastructure in terms of tooling and all the rest. And even if people have machinery available, it still takes a bit of expertise to go from blueprints/CAD drawings to a finished product; it's all too easy to design something that's not machineable. It took me quite a bit of practice to learn to hold tolerances.
Secondly, machining stuff out of billet can only go so far; you can't really carve closed hollow things for example (like rocket engines) To make anything, there's going to be major secondary operations; welding, riveting, or bolting or bonding stuff together. Each of those requires their own set of design considerations, and in at least some of the cases fall under the category of skilled trades.
Thirdly... none of what's been mentioned (machining, 3d printing, etc) really counts as "mass production"; they're all limited processes optimized towards one-offs really. In terms of time spent and material wasted making each piece, machining (CNC or otherwise) is close to the least efficient method possible. Making, for example, metal-style aircraft is a long process involving stamping and forming sheet metal and lots and lots and lots of accurately drilled holes with rivets put through them.
Anyway, just some information of a "reality check" sort; I encourage people who want their characters to be building stuff to take some of this kind of thing on board to figure out ways around, or whatever.
There's obviously going to be some groups making Stuff, Up Here. I wouldn't leave home without my mill and lathe and such, and I know there's a bunch who'd feel similarly. I have no doubt that there's going to be some quasi-Makerspace setups too that are open for use, but I also imagine they'll be pretty heavily booked up. And anyone who's making the effort to loft machine tools for their own use is going to be utilizing them pretty heavily. I mean, a basicish CNC mill starts at around 20 grand or broadly equivalent in time to convert a manual mill, plus it's about a ton or several of mass that has to be moved, plus infrastructure in terms of tooling and all the rest. And even if people have machinery available, it still takes a bit of expertise to go from blueprints/CAD drawings to a finished product; it's all too easy to design something that's not machineable. It took me quite a bit of practice to learn to hold tolerances.
Secondly, machining stuff out of billet can only go so far; you can't really carve closed hollow things for example (like rocket engines) To make anything, there's going to be major secondary operations; welding, riveting, or bolting or bonding stuff together. Each of those requires their own set of design considerations, and in at least some of the cases fall under the category of skilled trades.
Thirdly... none of what's been mentioned (machining, 3d printing, etc) really counts as "mass production"; they're all limited processes optimized towards one-offs really. In terms of time spent and material wasted making each piece, machining (CNC or otherwise) is close to the least efficient method possible. Making, for example, metal-style aircraft is a long process involving stamping and forming sheet metal and lots and lots and lots of accurately drilled holes with rivets put through them.
Anyway, just some information of a "reality check" sort; I encourage people who want their characters to be building stuff to take some of this kind of thing on board to figure out ways around, or whatever.