“In 1988, when we passed the Undetectable Firearms Act, the notion of a 3-D printed plastic firearm slipped through metal detectors, onto our planes in secure environments was a matter of science fiction,” Rep. Steve Israel, D-N.Y., said on the House floor. “The problem is that today it is a reality.”The law, as extended, requires 3-D guns to have a metal strip that would make them visible to metal detectors. Some Democratic senators wanted stricter controls, including a requirement that 3-D printed guns have permanent metal components.