I don't understand why 'printing' is exciting and dangerous
Well, for 'our' community, very little in the short term.
However, if we apply Moore's Law to the printers, they will become smaller, faster, and cheaper.
In 1989, I bought a color (barely) inkjet printer, and thought it cheap at $575. In 1999, I bought a color printer, which printed at twice the resolution, at 20x the speed, and cost what I thought was a very reasonable $120. In 2009 I needed to replace my old printer, after having to search long and wide to
not find a multi-function printer, the printer I found was under a hundred dollars.
When I first bought AutoCAD, it came on a stack (6 or 7, IIRC) of 3.5 'floppy' disks. When I upgraded, it was on CD-ROM. My last upgrade was just sent to me by email as an Image of the install disk. The next upgrade will be purely electronically submitted (which raises a question of what happens if I need to reload the thing).
Ok, so what?
Well, some of the people looking at the future see this: You need a shirt, you do not go to a store for it, you simply call up the pattern in your size and pass that to the 3d printer in your house. Maybe the place selling the shirt design bills you 99¢ lie a present-day iTunes music cut. You need a ladle in the kitchen? 3d printer. It's a potential future where "stores" only exist for perishables, living things, and antiques.
Such a future is something to behold. It's good to remember that the world will still need 'big' things. We will need cooling towers, powerplants, planes, trains, and automobiles--and all the place and people that make them.
How will that affect firearms? I haven't a clue. We have seen how the internet has changed the gun biz, though. How it has changed what we know about arms, about or fellow owners, about buying arms.