I have both printed parts that are commercially available and would fall under a protected design or function - after seeing it, modeling the same things.
Also I have made parts that may not be worth protecting copyright-wise, but cost twenty times as much (even online).

It's already reality to some degree, and same as MP3 will slowly creep up on the industry. Once it's beeing adressed it's probably too late;
It's amazing what a well working printer like the UP can do even without knowing a thing about 3D printing (that's basically how I started), and when software and hardware of reprap machines gets even easier to use it will spread more.
No doubt in a distant future we will have printers capable of printing on a much finer scale, and even if not on a nano or molecular level, I am sure 3D printers will be able to copy even more complex (and multi material) models.

It's allready fascinating that you can print working mechanic models with a SLS printer, without assembly required.
Even with a one-printhead FFF printer it' s possible to some degree, and I find it a lot of fun designing such models :-)