Industrial-scale 3-D printers are already advancing technology related to extremely dangerous weapons. The U.S. National Nuclear Security Administration (NNSA), for instance, is using these machines to manufacture models of nuclear weapons for testing. “While using 3-D printing to maintain the nation’s nuclear weapons stockpile, NNSA labs are advancing the broader science of the field,” the administration said in a 2016 blog post. Meanwhile defense contractor Raytheon has a 3-D printer that can manufacture 80 percent of a missile, and Los Alamos National Laboratory is using these machines to produce high explosives.

Not even an advanced machine can print weapon components without expert designs—but there are concerns that artificial intelligence could allow unskilled humans to come up with the necessary blueprints, thanks to a technique called generative design. With this process a user can give a computer a design problem and set requirements for the final result. The AI suggests many possible solutions, and humans pare down the results. For example, when General Motors wanted to replace its heavy eight-component seat belt bracket with a lighter version that used fewer pieces, engineers plugged these parameters into a generative design algorithm and 3-D printed the result as a solid piece of material. NASA recently used the technique to create a prototype lander for space missions.