The law prevents residents of New Jersey from downloading, purchasing or sharing instructions or manufacturing parts for printing a firearm using a 3D printer. These firearms, called “ghost guns” because they bypass existing control laws such as background checks and manufacturer’s serial numbers, have been controversial across the nation, with New Jersey Senator Joe Cryan describing them as “pos[ing] a serious threat” because of their untraceable nature.
The new law is a continuation of his ongoing efforts to tighten gun control laws in New Jersey. In June the governor signed six additional gun control laws, including mandatory background checks for gun sales, limiting magazine capacity for handguns, and stricter permit requirements for handgun owners. The new law was criticized by gun rights advocates while before the legislature as “redundant.” The National Rifle Association stated that it is “already against the law to manufacture a firearm without a New Jersey manufacturer’s license,” and that the new law served no purpose.
https://www.jurist.org/news/2018/11...control-bill-to-prohibit-3d-printed-firearms/