Just yesterday, the blueprint for the world’s first 3D printable gun was released onto the internet. Over 100,000 people downloaded the design and thus the era of the world’s most undetectable gun was born. This gun CAN be made completely from plastic and when you consider that anyone can buy a 3D printer (with the right amount of money) the era of guns that are not controllable at all from Washington has been born. Any attempts to control guns in general and make it more cumbersome to acquire will just from now on push more and more people into this new option. Since the world is the limit on what can be designed and printed, it is likely that guns that are currently regulated will soon become printable with these printers.
The world’s first printable 3D gun, the Liberator.
Thusly, gun control is going to die slowly but surely. With the prices on 3D printers coming down yearly with more and more hobbyists jumping into this new field, we will see more people every year with both the knowledge and the capability to manufacture a modern gun without a huge cost. This will in turn guarantee that any efforts to control guns will be met with the usual response: disobedience. And so in that effort any attempts to control guns will fail miserably. You can make an anti-tank gun illegal, but that does not stop anyone from downloading the design and printing it out themselves. With so much at stake in terms of safety, perhaps there needs to be an awakening of the dangers this could present.
While I personally am against most forms of gun/arms control, I tend to think the danger in people being able to manufacture any type of weapon they want is very scary. People could print out huge guns for just the price of one 3D printer and this opens up avenues where criminal enterprises will find it much easier to acquire illegal arms. This danger must not be over-looked in the future as we gaze upon what is possible with these 3D printers. It should be said that you can not print these guns with a lower end 3D printer (1000 bucks is the cheapest) but with the technology improving like it is the cost will come down. 8000 bucks for the ability to manufacture anything you can design a blue-print for in a computer? Well the dangers of this will become apparent soon enough. But we can all breathe a sigh of relief for now as the technology is too new and the gun designs not there yet, so therefore until it does catch up to practicality most people will not even realize what a 3D gun is or care. Perhaps this is the saving grace in that this slowness of adoption will force people to think it through clearly before we just simply ban 3D printers.
So for now we can rest easy, but there will come a time where gun control will become secondary to “3D printer control” and thusly no Government in the world will be able to regulate items that can be manufactured. Perhaps this is for the best since society will have to find a way to deal with technology just like always. The worst thing we can ever do is simply blindly ban things because they are scary. Just like guns, 3D printers are a tool that can be used for good things or for bad things. It is all about the person’s intent and this fact is probably what makes society as a whole safe. Sure, it seems scary that people can manufacture weapons that can go through metal detectors and are untraceable, but in the end the best we can do is to be aware and respond with well thought out ideas versus cheap and quick emotionally driven decisions that end up throwing the world backwards into fear and panic. Perhaps there is a way to change the plastic compounds that these machines use so as to make guns detectable in a new way? Or perhaps we could add digital fingerprints to the process so that you can figure out WHAT printer printed what? There are a ton of options in terms of regulation, but the technology is going to have to catch up to the necessities of accountability.
BenfromMO 
It is true you can print a gun, but currently, the most shots one has gotten from one of these printed guns is five. These were underpowered shots, it should be noted.
What you cannot print is gunpowder. You may be able to print the brass, but I doubt you can print a primer. The limiting factor in 3D printers and guns will be the gunpowder/ammo. Look for licensing of all individuals purchasing any kind of gunpowder or primers, plus loaded ammo. It’s the way to slow the usefulness of the 3D printers for a fairly long time. I cannot imagine the government not jumping in and starting banning these items ASAP. Look for it.
Benfrommo: While it is true that ammo is going to be the weak link so to speak in regard to a 3D printer.. but that is simply a technical hurdle that can be overcome with different designs. The Government could regulate ammo, but there are too many people who make their own ammo for that to have much of an effect long-term and yes, I do believe you are right when you say the Government will do this and that it is just a delaying action really. This is simply because gunpowder is not a hard substance to create from raw ingredients. But the more they ban these things at this point, the more popular it will become. Something to consider, what about making your own drones? After an aerospace engineer designs the blue-print, this makes it an easy task to create your own airplane with a 3D printer. Combine it with a smartphone and suddenly you have a drone which you can see out of (camera) and direct via the smartphone. All in the comfort of your living room. Kind of a scary thought, isn’t it?