Facebook lifts ban on spreading 3D printed gun blueprints

Facebook will allow some users to spread and promote blueprints for 3D printed firearms on its services, potentially opening the door to sales of untraceable "ghost guns". 

The social network said it would let "legitimate" gun shops and online vendors offer instructions for printing so-called “downloadable guns” in places where it is legal to do so. 

The new policy partly reverses a total ban imposed last August amid public fears that unregistered, untraceable plastic guns printed in homes and garages could proliferate across the USA.