3D printing... To explain what it means is impossible. I can't even fully get my head around it.
3D printing is the future revolution, and I mean that figuratively as well as Literally. Nations will topple because of this technology. Not today, tomorrow, or the mear future, but within our lifetime. Today 3D printing is like the old computers. Apple IICs, maybe 486s. Antiques that have little in common with what is to be.
To understand what I am saying, realize that I am currently composing this on a device smaller than my hand over 1500 miles from home, in the middle of nowhere, and this isn't even a great feat anymore!
3D printing...
To print an object you need the printer of the right detail to work in the tolerances you need, appropiate materials in the right format, power for the printer, and instructions for the printer.
Now a 3d printer is an object that can be printed. A solar cell is also a printable object. If you can design a 3d printer that can reliably reproduce itself with the same tolerances, you can create a self-replicating manufactory that is only limited by materials. That means little for us at first. It will slowly toss manufacturing on its head, shifting us to more materials processing and less fabrication. It won't shut the smart ones down as materials won't be exact replacements and people will want choices. Many things that are currently artificially restricted like guns and smartphones will be accessible to anyone. In the US you would see very few effects of that, as well as most of the developed world at first. Heck, it might not even catch on that great here, but...
There are places in this world rich in resources but poor in finances. This is where 3d printing changes the world. The technology trickles out of the first world, and these poor nations suddenly can jump up to our quality of life technologywise overnight. Nobody can hold entire groups back, and no place is too remote to have modern technology.
You might sputter about any number of technologies that cannot be 3d printed, but it is all an engineering problem then. one that once that can do flag turns from f to t on whatever item you name, becomes impossible to flip back.
So, two things happen. One, labor prices change globally. Two, material costs rise dramatically. Where it has to be imported, it becomes exponentially, as resource producers consume more of their own product.
What does that mean? I don't really know. Its much more effect than unregulated firearms though.
If you want to be well off in the future though, find a flexible resource extraction company that works locally and invest big in them.