Here is an excellent White Paper guide written by Michael Weinberg on how to licence elements of your 3d printed / 3d printable object. It is a must read for anyone dealing with 3d printing and design!
Here is an short overview from the document:
A Three-Step Process In order to understand what it is you are licensing, this paper proposes a three-step process:
Figure out which elements of your object or object file are eligible for copyright protection
This can be much harder in the world of physical objects than it is with exclusively digital works. Unlike with code or photographs, with physical objects you may actually have to search out what parts are and are not protected by copyright. You may also need to make a distinction between the object and the file that represents the object—something that rarely occurs in the more traditional copyright world. While this can be complicated, this paper will try to make it as intuitive and straightforward as possible.
Understand what copyright does—and does not—allow you to control
Although it sometimes can feel otherwise, a copyright that protects a work does not control every use of that work.1 Understanding what your copyright allows you to control— and what remains out of your control—is critical to thinking about how to license things. For example, you may have a copyright on a file that represents an object, but not on the object itself. In that case, you should be clear-eyed about the fact that even the most restrictive license on the file will not stop people from reproducing the object without your permission.
Choose your license
After you understand what parts of your work are protected by copyright, and what that copyright protections actually mean, it is time to think about licensing. Once you understand what you have the legal right to control, you can start deciding how you want to exercise that control. This Paper is Only About Copyright Your 3D object might be protected by more than copyright. It could be protected by patent, or by trademark.
So why is this paper only about copyright?
Mostly because copyright protection is free. If you create something that is eligible for copyright protection, it automatically gets copyright protection free of charge. There are good reasons to register your copyright, but registration is not required for protection. This means that you get a copyright without ever filling out paperwork, consulting a lawyer, or even wanting it in the first place
Here you can download the entire guide in PDF format:
This White Paper was published by Public Knowledge on March 06, 2015: Public Knowledge is a non-profit Washington, D.C.-based public interest group that is involved in intellectual property law, competition, and choice in the digital marketplace, and an open standards/end-to-end internet.
Only issue that needs further clarification is how 3d printing copyright works in international environment. You create a 3d object in one country, publish it on a repository in second county, someone in third country downloads it and does something against your licence...
THE BATTLE OF COPYRIGHT