OK, it's a very small house. And it's the Russians, so it could be a Potemkin house, or they could be cheating in some other ways: maybe the printer only ran for 24 hours but they're not mentioning that it stopped every fifteen minutes for teams of plumbers and electricians. But it's also... the future.
And I wasn't ready for it. Here I've got one book in a series finished (AWAKENING) and I'm a quarter into the book that happens before that one (INSURGENTS) and I was only giving my 24th-century colonists the ability to print slabs of wall-like stuff that had to be hinged together. That's what you get for not keeping up with technology! Ok, not a vital part of either story, quick revision, now they've got building printers.
Now reading a tad more diligently, I came across a story about a 3D printed RPG. My son-in-law commented that that required them to print steel...
Mental headslap. Of course they can print steel. Even I, with nothing but a jewelry kiln and some basic modeling tools, can make steel shapes! The technology's been there for years. All you need is a base of tiny steel particles in a moldable binder and some way to heat the shape at the right time/temperatures to (a) burn off the binder and (b) sinter the steel. OK, there are a few other issues, but that's the basic idea.
It started with precious metal clay, you see, which gave jewelers fine silver or gold in just such a binder. That's been around for what, 20 years? And after that came copper clay and bronze clay and steel clay. Any of those "clay" bases can be thinned to make "ink" just by diluting them.
So... my guerillas in INSURGENTS have just stolen a printer that makes solar-chargeable blasters. And the steel "ink" to put in it. They may have melted their first couple of attempts (Hey: I know a LOT about failures with this material) but they are now figuring it out with the help of an antique jewelry-making book. I feel it's a happy combination of using what I know combined with what I just found out about.