So if this passed it would be illegal to have a computer controlled machine that built a gun component, whether metal or plastic, by adding material layer by layer, but it would remain perfectly legal to make the same item, whether metal or plastic, by starting with a solid block and having a computer controlled mill cut/grind away CNC Milling. I don't think these people have thought this through completely. I get that 3d printers are getting cheaper everyday, but so are CNC mills. My nieces husband just ordered a machine that can do both 3d printing and CNC milling just by changing the head for about $1000.