I'd say we was only a few years away from that already I was given the chance at 14 to buy a black market hand gun with ammo from a guy driving around in an escort van, with all types of gun's in it.
I'm sure with the airports already installing Total Recall type x ray machines. And they could/will make software to stop the average Joe from being able to use the plans, and I would guess safety measures are already being put in place granted I know myself anything they do can be worked around to still make weapons but don't think it will be as easy. I still think it's a great idea even if they will always be people that can abuse it for bad thing's.