At first glance, the answer seems extremely simple; 3-D printing is obviously a friend. How could 3-D printing possibly step in the way of the anti-copyright or those who want to see a change in the status quo? The answer is complex and there are multiple threats that I see 3-D printing creating.
First- a blatant copy is not a remix. Remixing has become more and more accepted, and understood in the internet age. While 3-D printing is extremely creative- the outputs and products of it's existence might not be. When it becomes possible to download a file of something, then print an identical copy of an object some while argue that creation will stagnate. Remember the old anti-piracy ads saying "You Wouldn't Download a Car"? Well, to be completely honest I probably would. I'm no saint- I have definitely pirated music and movies before (I still miss you, LimeWire- You really helped me on my middle school budget). 3-D printing could allow for those around the world to access certain objects they may not normally be able to get their hands on. The government has yet to regulate 3-D printing, it is still at a stage where it does not threaten production of goods, and the economy. And actually, at a large scale 3-D printing is relatively expensive to get into so the manufacturing industry is extremely interested. So perhaps I'm wrong, this new tech won't get regulated and it will help America get back in the game of mass manufacturing.
Or... it could get regulated. Take a look at this. This is a 3-D printed gun that is easy to put together. The file is free and easy to access, and requires little to no knowledge of firearms to assemble.
A company named Defense Distributed has published open-source versions of the handgun shown above, as well as a printable AR-15 lower receiver. My younger brother, being the young, wild, free and slightly crazy libertarian he is sent me a video recently. Defense Distributed has developed something in the vein of 3-D printing, called the "Ghost Gunner" you insert what is called an "80-percent lower receiver" and it mills it out- creating a completely anonymous lower receiver that anyone can make. The rest of the gun could be bought by a seven year old on eBay... legally.
Here is a video by Defense Distributed mocking the government, and showing the new invention in action.
I am extremely excited for 3-D printing. I think we are potentially on the brink of a new, modern industrial era. I would just hate to see 3-D printing shoot itself in the head.