I didn't think much about 3D printing when I first saw it.
I thought it was interesting, but didn't grasp the impact it's going to have. At CES, there were models selling for around $500, with very professional units just around 2 grand. I saw sculptures, representations of people, and just about anything else you could think of.
But the light didn't really go on until I returned home and read about the Lux DIY medium format camera designed by Kevin Kadooka. What Kevin has done is create a lovely, functional film camera, with its components output by a 3D printer (sans electronics and the lens).
Kevin is making the plans available to anyone who wants them, so you can build your own Lux with the electronics and 3D files openly available.
Think about this for a minute. It's print on demand for objects. You could design anything, produce the 3D printing files, share them or sell them, and then others could create those objects at home.
I'm not sure how this is going to play out. But I think the boundaries are still beyond my view. And I'm sure that 3D printing is going to change a number of things in our world.