People actually are concerned about homemade pistols and SMGs being used by criminals, though. It comes up quite often in Europe these days, especially in UK.
And, yes, in principle, 3D printing doesn't really bring anything new to the table since you could always machine a gun, and the tools to do so are all available. The difference is ease of use - 3D printing lowered the bar for "people competent enough to manufacture dangerous things" enough that your latter argument no longer applies.
FWIW I don't know the answer to OP's question even so. I don't think we should be banning 3D printed gun designs, or, for that matter, that even if we did, such a ban would be meaningfully enforceable. I don't think 3D printers should be banned, either. This feels like one of those cases where you have to accept that new technology has some unfortunate side effects.
And, yes, in principle, 3D printing doesn't really bring anything new to the table since you could always machine a gun, and the tools to do so are all available. The difference is ease of use - 3D printing lowered the bar for "people competent enough to manufacture dangerous things" enough that your latter argument no longer applies.
FWIW I don't know the answer to OP's question even so. I don't think we should be banning 3D printed gun designs, or, for that matter, that even if we did, such a ban would be meaningfully enforceable. I don't think 3D printers should be banned, either. This feels like one of those cases where you have to accept that new technology has some unfortunate side effects.