I don’t think gang bangers will like the nickname “Stumpy” they will get after their piece ‘breaks apart’ 
FYI, the files needed to produce an M16 etc… have been freely available on the internet for decades.
http://www.biggerhammer.net/ar15/cad/
I also agree that CNC would be much more practical than a 3D printer (I own both) and the skill needed to produce a firearm with home shop type tools is not really that high.
If the big difference between 3D printers and conventional machine shops is just ease of use, then a better thing to worry about (if you’re going to worry about such things) would be fully-automated machine shops. I see no reason that a conventional machine shop could not, in principle, be made just as easy to use as a 3D printer.
There is very little difference in the “difficulty” of running either a CNC machine or a 3D printer. The CAD/CAM portion is the hardest part and is shared between the technologies.
As for manual milling the DRO or the Digital read out also makes milling much easier.
But the real huge difference is what with subjective machining you are using a material stock that is much stronger and has strength and physical properties controlled by people in labs. 3D printers are like small CNC glue guns and while their parts are quite strong they will never be as strong as commercial stock.
Plus you can just make parts to the existing blueprints, you don’t need to personally engineer around the materials limitations.
Are they going to print the bullets, too?
Hmm. I could see restrictions being made at the raw-material level. What if printed ammunition requires 8 materials, seven of which are readily available at any online maker shop, but the eighth requires a license and to be picked up in person with ID check, etc, etc?
Heck, Captain Kirk made a working cannon out of dirt and rocks.
People are focusing too much on common weapons I think. Assuming that 3-D printers (or their technological descendents) reach the point that they can print things like rifles, they ought to be able to print more powerful weapons as well. So in that scenario we can expect to see things like gangs and lone lunatics with what we’d think of these days as serious military weaponry; limited mainly by the size of the printer or their ability to assemble the smaller components it produces*. So some lone lunatic fires an RPG or .50 machine gun into a crowd instead of an assault rifle, and criminals can RPG squad cars. This would also have implications for terrorism since they wouldn’t have to smuggle weapons; they can just make what they need after arrival, at least in any place that has 3D-printers.
*So presumably no running off a copy of an APC or tank even if you can print armor, unless you presume some extreme libertarian situation where the government refuses to regulate even the kind of building-sized automated manufacturing faculties that could make something like that.
Extreme libertarian? They don’t regulate it now. What’s stopping you from building a tank? It’s just stuff welded together with an engine in it. Nothing about that is regulated; granted, the specific type of armor used by NATO countries is a secret, but a steel tank will kick enough ass for insurgency purposes.
Purchases of steel, welding machines and consumables, and other stuff like that is not regulated.
Not yet. Will be before some unsanctioned private enterprise rolls out its first tank.
Why? It didn’t happen after Marvin Heemeyer.
I think in most places, if word got round you were building some sort of armoured vehicle in your garage, the authorities would pop round for a friendly chat, even if there wasn’t a specific law against building a tank in your garage.*
*Especially since it’s legal to own an actual tank in many places, provided it has no armament.
It wasn’t a real tank, and didn’t have a working tank gun & ammo. He didn’t even manage to kill anyone but himself.
And there isn’t likely to be as much worry about someone doing the same thing more destructively given the difficulty of one person building the thing. Whereas in this scenario, we are potentially talking about any random person being theoretically able to download tank plans from the future version of Pirate Bay, upload it into the computer and just push the “build” button. A few regulations and safety features to help prevent this just might be in order when and if such automated manufacturing becomes available.
Well, putting a five-pound limit might help, unless someone makes plans for a tank you can put together like a big LEGO project…
Bigger than that. I expect that eventually we’ll be seeing small automated factories that can build large objects like vehicles on demand (although likely not just using 3D printing). People aren’t going to want to have to assemble their new car by hand either.
So, what kind of PSI can materials made using 3D printers and CNC withstand? As others have likely already said, the tricky part of a gun is the chamber and barrel. Everything else essential to the gun you can make in shop class.
Also, do 3D printers make molecules? If not, then you can only make explosives if you’ve got explosives molecules which can be controlled in the same way that regular molecules are.
Apparently.
If a machine can make drugs, it can make explosives.
I’m not quite sure you get what you’re asking. 3D printers and CNC are completely different technologies. CNC (computerized numeric control machine shops) are essentially the method that the big firearm manufacturers use in their factories. They probably have more specialized machines than the home DIYer, and they certainly have more of them, but the methods are the same. So CNC can certainly make strong enough gun parts.
Yes. However, making rifled barrels is old tech. Rifling machines are certainly big and single purpose, but they have existed for over a century. There are already independent barrel makers selling their wares online. The chamber is simply a lathe operation with a chamber cutter.
I am pointing this out to illustrate that at the current level of 3D printing tech, the fears are unfounded. The ability to manufacture firearms at home is already with us. Real steel guns, not soft extruded ABS plastic out-of-tolerance things. rat avatar is correct in his statement about the CAD/CAM software being the hard part. He is also correct about the blue prints having been available for a very long time.
Now, if we are actually discussing Star Trek replicator tech, then all bets are off. But here in 2012 real world capabilities, you should worry about home owned CNC mills, not 3D printers.
And never, ever inspired copycat kids to try it out with the saltpeter and sulfur that were readily available on drugstore shelves in those days, and a charcoal briquet or two from dad’s barbecue supplies.