I can't see anything beyond renewing the already existing laws, which- though I admit I haven't read them- would seem to make sense. We all have an interest in firearms that can't be detected with metal detectors being illegal until technology produces another widely-available means to do so.
But haven't non-metallic- either plastic, or ceramic- been produced before outside of the 3D printing? IOW, is it the plastic firearm that's "new", or just the relative ease of producing it?
Mosin-Nagant Custom Shop/Bent Bolts
Gun-Kote/ Cerakote Refinishing
Criterion Barrels/ Savage Re-Barreling