Castanet is reporting that "A Quebec-based anti-gun unit says 45 people have been arrested and 440 guns have been seized in raids targeting manufacturers of 3D-printed or "ghost" guns across eight provinces." I don't know how real 3D guns are. I don't know. I'm not even sure how a 3D printer works. Obviously if they work it's going to become a problem because criminals will use them. The gun in the picture looks kind of dumb.
Obviously you're going to need a steel barrel and order some kind of hammer or striker mechanism to fire it. Maybe that's what they're doing. It's "legal" to order barrels and firing mechanisms seperatelty. Perhaps you should require a firearms license to do that.
I assumed you already did require one. If not, they should change that given the ability of printing up the rest of a gun on a 3D printer.
As far as them being untraceable GMAFB. All the stolen guns criminals use are untraceable. That's why they often leave them at the scene and call them throwaways. They leave it at the scene because it's not traceable but if they are caught with it after the fact they could be implicated.