In the past few months there has been a lot of debate over guns that can be made with a 3D printer, which would make it easier for people to get a gun. But there's also a push happening in the tech startup world that is focused on making guns safer. "Smart gun" technology has been around since the 1970s. While the tech has evolved over time, the idea behind it has stayed the same: that only the rightful, registered user of the gun can operate it. Marketplace Tech guest host Amy Choi talked with Alex Yablon, a reporter at nonprofit newsroom The Trace, to find out why this technology hasn't come to market. (08/13/2018)