^ Lennie gets it. What's happening now isn't the point, it's only a stepping stone. The important take-away is what will be possible in the near (~10-30 yrs) future.
Technological development is the ultimate democratizing force in human society. It's what enables commoners to do things that were once the purview of rich governments and militaries. Just as the automobile gave the once-horse-dependent masses access to rapid, personally-controllable transportation, just as my cheap Android cell phone has more computing power than a B-2 Spirit, technological advancement is the enabler of the masses. Today's 3D printing of guns is just the tip of the iceberg.
The home-brew fabrication process will, inevitably, get faster, cheaper, and utilize increasingly superior materials. Printing guns that are solid and reliable will become a trivial endeavor -- but that's not the point. Technology has a way of trickling down to the masses. What happens in the future when nanorobotics becomes not only ubiquitous, but dirt-cheap for individuals to create and customize? What happens when people can create devices that are nearly on par with nuclear weapons in destructive power?
This isn't an 'if' but a 'when', and most important will be how we deal with it. Do we accept an increasingly locked-down world where concepts such as individual liberty are a relic of the past in order to ensure some vision of perfect security? Or do we finally accept that mutual respect, peace through a live-and-let-live ethic, is the only way for humanity to survive the coming age where any single person can, with minimal financial investment and time, create and deploy various manner of weapons of mass destruction?
It's already been demonstrated time and again that legislative bodies are woefully behind the times when it comes to technological understanding, let alone forming appropriate reactions. How they're going to deal with what's coming in the next few decades is anybody's guess, but personally I'm not optimistic. We'll either live in a completely locked-down dystopia that would give even Orwell himself nightmares, or we'll have reconciled our differences to the point of non-aggression -- or we'll be extinct.
The genie's out of the bottle, and the power it's giving us shows no sign of slowing. What we do with that power will determine whether we as a species have a future or an epitaph.