The article is too long to post, so here's the link: http://news.yahoo.com/you-don-t-bring-a-3d-printer-to-a-gun-fight----yet.html The upshot is for quite a while people have been able to either make a one-shot zip gun with $20 and a trip to home depot, or a decent gun with a few thousand dollars of CNC equipment and some skill, but new 3d printing technology potentially lets you make high capacity firearms from equipment that costs less than many guns do a file with the plans you can download off the internet. The trick is somebody making those files and distributing them free, and there are groups out there working on that now. Currently you'd still need a metal barrel, but again that's a simple trip to home depot if you're looking for something that doesn't have to be very accurate (such as for sticking up a teller or going on a point blank rampage). The point being that the idea you can use laws to keep guns out of the hands of crimals is getting buried under modern technology.
People would only make Jerry-rigged guns if they are outlawed or very hard to get. In the US used guns very inexpensive and commonplace. No one with the intelligence to make one of these contraptions would risk blowing off their fingers or hands firing one when they can go to a pawnshop or dealer and have something safe. And the people who commit crimes, and shouldn't have them by law do not care about gun laws. They will almost always use a stolen or illegally obtained weapons. In places where guns are hard to come by legally, like South Africa, all kinds of homemade and uh, rigged weapons are found. They are not made with the high tech machinery in your article.
I don't know that I disagree with any of that, but I'm not sure what you're trying to drive at. My post was related to people who think that you could at least keep reliable repeating firearms out of the hands of criminals while draconian gun laws. What the new technology does is combine the best of cheap low skill improvised single shot firearms and high quality smithed firearms that require some skill and equipment. I imagine 3d printed lowers wouldn't have the accuracy and especially wouldn't have the longevity of commerical firearms. But for criminals those don't matter so much.
As I made my own AR weapon from a blank lower receiver (That did require registration) and Bushmaster parts, I don't think the plastics would be that durable---maybe with carbon fiber or some other material--maybe. AR lowers are already being made by guys in their own garages and machine shops---but for the garden variety criminal here in the US, none would bother doing it. My views are, don't register or ban guns for honest citizens, register and punish felons for their actions.
A gun is really not that difficult to make, for anyone that's not stupid, as is the least bit mechanically inclined. The danger is that people would make unsafe guns and blow off their hand or lose their eye sight firing one of the things.
