I know that this technology is the new up and coming scare tactic for the media. Regardless of the improvements this will have over the years, you will still be only able to make parts that have no real stress on them. Look at the AR-15 someone put together. They still had to use a complete metal upper. The receiver that is printed lasted only a handful of rounds. Finally broke at the buffer tube. Image a 1911 frame, it does have a bearing surface and alot of force acting upon it. Try that with plastic. The AR-15 was the easiest to make, as it really has no force acting upon it, except by the buffer tube where it broke. And without metal internals and a metal upper, it would never function.
The technology will get better. But we would need super huge advances in polymer science to be able to make a part with the strength needed to be a bearing surface or any type of internal mechanism,ie hammer, firing pin or such. Perhaps still in my lifetime, but I would think ray guns would become more pactical before this tech can produce a complete firearm for a relatively low price that anyone can afford to put in the basement workshop. All this just IMHO.