Why would they bother with a single-use plastic gun?

Potentially because it could be cheaper or easier to acquire, easier to get past a metal detector, and easier to dispose of / more difficult to trace.

The same can be said of a disgruntled divorcee who wants to assassinate their ex-spouse or judge in a courtroom. Print two: one for murder and one for suicide.

Edit: Or a middle class kid who doesn't know any criminals from which to buy an illegal firearm but does have access to a 3D printer and torrents.

I think Ryan_G makes very valid points. AGAIN with the disclaimer that "I am not sure it's a good idea" does NOT equal "I think it's a bad idea."

You know the government is getting ridiculously desperate when it resorts to this sort of thing:

The alleged claim by the government came under ITAR, which is a law that regulates the export of materials deemed to be of interest on national security grounds.

For instance you cannot export (without specific clearance) things like high-quality night-vision equipment. You can buy that sort of thing as a civilian in the United States, and it's perfectly legal. There are plenty of legal reasons to want that sort of equipment.

But you cannot export that technology to other nations with a determination that the export will not land in the hands of the "wrong people" in other nations, particularly those nations that would (or might) use that technology in warfare against the United States.

That seems to make sense on a facial level.

But applying ITAR to information is a different thing entirely. First, it's pointless, since once the information is out -- it's out. There are literally hundreds of thousands of copies of these files around the Internet already; they're everywhere. Trying to stuff the genie back in the bottle is a waste of time.

There is also the legal reality on this -- ITAR exempts "libraries" (for obvious and appropriate reasons) as it recognizes that you're wasting your time to try to stop information alone from being distributed.

That the government went here to try to force Distributed Defense to take these files down shows exactly how desperate they are. Not only is this law unlikely to hold up when challenged (and I presume it will be) that they used this excuse says quite loudly that they could not come up with an actual, legitimate legal means by which they could stop the firm from doing what it is doing -- that is, using technology to restore and protect the Second Amendment.

Technology is a funny thing -- it frequently outruns the desires of those who would exert control to project their power. Sure, the military and government use technology to spy on people, including Americans. But Americans and others can use technology to make it very hard for government to spy on them, should they so wish and be willing to take the steps necessary to do so.

In the end analysis what The Government is doing here is pointless; it cannot "win" this fight as the data is already out in the public.

But what it can do, and is doing, is throw a temper tantrum.