I somehow doubt that they made a barrel, properly chambered for the round, on a 3D printer or am I a decade behind the times? Question?
I believe 3d printing sinter metals has been possible for some time, but I don’t believe it’s currently at a more industrial level. Even if you could 3d print a barrel out of sintered metal, you’d still have to at the very least finish ream the chamber to size. How that barrel would hold up to even a few rounds of suppressed fire is something that would probably be questionable, blowback is a thing with suppressors.