The low end 3d printers look like they cost about $4,000. Cool technology but the old fashioned metal tools are probably cheaper and easier.
google “maker community”.
These are local community fabrication shops open to members.
Membership is monthly, and is affordable.
Upshot: these maker workshops could buy one or two of these printers (they usually have CNC’s), and you could go pop in a disk and use them.
Missed this when it first was posted. Low-tech may indeed
be more feasible for many. In any case, those much more
knowledgable than I have said: guns are easy. ammunition
is hard.