Well, in the US there's currently a lot of effort going into attempts to tackle "ghost guns". Restricting ammunition may be better from a practical perspective (I don't know for sure) but it's harder from a 2A perspective. But none of it is targeting the 3D printers as Doctorow feared. I don't know if this is because the impact of 3D printing on homemade guns and other potentially lawbreaking activities has been limited or something else. I do think there's a general suspicion of having devices try to do something about lawbreaking activity they might enable, think of the backlash against Apple's CSAM scanning proposal. This might be Hollywood's fault, the idea of devices playing cop immediately makes people think of their computer ratting them out for watching a pirated movie.