Varunik, I want to make one thing clear. I am not coming down on you for your post. I am hopefully educating some IFG members about the truth of the above article.
Before everyone panics, gets their pretty little panties in a wad and goes: "OMG! The sky is falling, think of the children", please remember that he is only producing the lower receiver. This is another case of the media sensationalizing the ordinary. Must a been a slow news day when they penned that article.
You know, TC probably gets pissed off at me for always mocking the media but how can you not, when you see crap like this.
The lower receiver of an AR-15 is the serial numbered part of the gun and therefore considered "the gun" from the BATFE's standpoint. You need to go through a background check to purchase that part. If I walk into a store today that sells lower receivers, I should be able to pick it up, get checked out, pay for it and walk out in about 15-20 minutes. Filling out the Form 4473 takes about exactly three minutes, if you want to write clearly and legibly. By itself a lower receiver cannot do anything. You still need to purchase all the parts to make it work; sear, trigger, hammer, buffer spring and tube, trigger guard, assorted other springs, pins, safety lever, mag release, bolt release, blah, blah, blah. It also needs an upper receiver, a bolt carrier group, a barrel, hand guards, pistol grip, buffer tube, gas block and tube, sights, etc.
Keep in mind that the now defunct Cavalry Arms produced polymer receivers (someone else has the patterns now) for over ten years. There are very few stresses on the lower receiver. If you could get it to stay together to hold the upper receiver and all the mechanicals, you could build it out of paper mache (OK, I'm probably exaggerating just a little but you get the point).
This is what an AR15 lower receiver looks like.:
A rendered image
A CNC machined lower.
Now here are all the parts you would need to make a complete lower:
Here is where you can download and look at the print:
http://defcad.org/defdist-ar-15-lower-receiver/
Here is an article about building a complete lower.
If you printed just the lower receiver, you will have to purchase everything else shown here to make the lower.
It still cannot fire. You need a complete "upper" to mate with it before you can do that.
Now here is what a complete upper looks like:
Once you have a complete lower, a complete upper and a magazine, only then do you have a complete rifle.
Remember, this is not new technology. The company that I work for has been sending 3D drawing files (.sldprt, etc) out to be rapid-prototyped for over fifteen years. Rapid Prototyping has been going on for a number of years before that.
Numerous manufacturers now make polymer lowers. You still have to buy a bunch of crap (pretty much everything else) that you cannot make on a 3D printer (or without a $500,000 CNC machine and a hammer forging machine for the barrel)
A gun to me is a complete firearm to which you just add the ammo and then pull the trigger on. Parts of a gun are not "A Gun".
So NO, You cannot "print" a gun..... yet.