"We need to engage software developers, technology experts, and leaders in the 3D printing industry to identify solutions in this fight," Monaco said. "You know your industries and this technology better than anyone.
"We will keep at this work - trying to stop the proliferation of MCDs. Our ask is … that you do the same."
So it sounds like they want the 3d printing industry to prevent machine guns and conversion devices from being printable on a software level. Just like modern inkjets can't print money. I'm not really sure how that'll work on the open source side.
It's not meant to stop it entirely. Just add a barrier that stops casual interest.
Just like a lock on the door to your house. No real burglar is going to pick your lock, they'll just kick the door (breaking your almost surely incorrectly installed doorframe), or throw a rock through the window.