Reuters reports that President Donald Trump on Tuesday raised concerns about the sale of plastic guns made with 3-D printers. The warning came a day after several U.S. states filed a lawsuit against the Trump administration to block the online publication of designs for such printable weapons. Referring to the National Rifle Association, Trump said on Twitter, “I am looking into 3-D Plastic Guns being sold to the public. Already spoke to NRA, doesn’t seem to make much sense!”