Why is the Trump team saying yes to the 3D printing of guns?

Edited to add:
Esp. considering this:
“3-D printed guns are functional weapons that are often unrecognizable by standard metal detectors because they are made out of materials other than metal (e.g., plastic) and untraceable because they contain no serial numbers,” the state officials said in the lawsuit. “Anyone with access to the CAD files and a commercially available 3-D printer could readily manufacture, possess, or sell such a weapon.”
Latest news about it:
https://www.nytimes.com/2018/07/31/us/politics/3d-guns-trump.html