I just don't see how it matter what tech made the gun parts
Legally, it shouldn't matter. Practically, 3D printing has big implications for gun right/gun control.
I disagree. It took me a while to put my finger on it, but I finally worked it out. 3D printing is not a revolution, it's just popular. You can put a CNC mill together for between 1.5x and 2x the price of a hobbyist 3D printer. It will work with metal and it will produce a smoother and more accurate final product. Why is 3D printing being singled out when CNC mills are a much more viable problem?
Think about the difference between "pre-iPhone" (or "pre-Android") mobile devices, and the current app ecosystem that now exists. What was the "tipping point?" Some would argue that it was the next generation of technology, with development tools being advertised by the various organizations. Think about 3D printing being that next generation of computer-developed manufacturing. What plans are available online for making a gun or a magazine for a gun on a CNC platform? I don't know, because I have never looked, because I have never for one second thought I could afford a CNC setup. I have followed links from some of the 3D printing-hype articles, to look around a bit and see what is available for download on various 3D printing repositories. I already saw what happened to the prices of regular printers between 1996 and 2013, so it isn't too difficult for me to imagine being able to afford a 3D printer one day in the near future (regardless of the fact that I know the economics of printers being loss leaders, etc.).
3D printing changes the world so that making a gun no longer requires specialized equipment nor specialized skills. So from the gun-control point of view, there is a real risk of guns being made in secret, in a decentralized way that is hard to detect, and being trafficked outside the existing system of licensed dealers and background checks. So the old framework of gun-control laws won't work. A would-be criminal who can easily make his own gun neatly evades the whole system.
This simply isn't true. Home CNC has been around for over a decade, in the $2000-$10,000 range. The more DIY you want to get, the lower it goes. The software is open source (LinuxCNC) and the electronics are simple.
On the other hand, no one knows for sure what technological developments will come tomorrow. Some people may expect 3D printing to become significantly cheaper than the $2-10K range that point out exists for CNC technology. Also, when this happens, they could very well develop these extremely cheap 3D printers with drivers and applications to design new objects for Windows (along the lines of even "less specialized skills" required).
There is just a mindset difference between the hackers (very dedicated hobbyists with specialized skillsets) who used to build those Phreaking boxes for the phone system and script kiddies of the late 90s through today. For various and subtle reasons, 3D printing appeals to the latter more than CNC technology might. I am not familiar with the nitty-gritty enough to put my finger on it. CNC is inherently a subtractive process. 3D printing is in theory much more like a Star Trek transporter/replicator technology. This really appeals to geeks.
There big question is, what will replace the old legal model? There are many possible things the legislature could try, from giving up on gun control (unlikely) to trying to regulate the plans for gun parts (impractical, as we know from file sharing) to trying to clamp down on the printers themselves (scary).
This is a good question. The problem, though, is that the ship has sailed on controlling the printers. There are so many plans available from so many people (see file sharing) and the printers themselves are cobbled together from hobby electronics and parts you can buy at Home Depot.
This is exactly why 3D printing is more revolutionary than CNC. From what I have seen in other technological evolution, even the most "revolutionary" technology is really still an evolutionary technology that just reached a tipping point.
This is how the tech used to make the gun parts matters.
You may be right that someone in government will try and crack down on the printers themselves (Think of the children!), but it won't be long after that happens that someone with a CNC mill starts producing "controlled" items. The technology used is irrelevant.
I can totally see that happening also.
Thanks for the discourse. I have been trying to walk down this path mentally myself recently.