3 Steps for Licensing Your 3d Printed Stuff by Michael Weinberg. CC BY-SA 3.0 A set of instructions for how to license 3d printed materials https://www.publicknowledge.org/assets/uploads/documents/3_Steps_for_Licensing_Your_3D_Printed_Stuff.pdf
Relevant content in the unit: Unit 3.2, Acquiring Essential Knowledge, What types of content can be CC-licensed, suggested additional content (related to both paragraphs in current content).
While the primary purpose of this paper is about 3-D printing, this resource is a great overview of copyright law related to electronic files, whether they be photographs or the files for a 3-D printing project.
This is an especially good resource for those interested in specific examples of the delineation of the functional, non-copyrightable aspect of a work and the artistic expression, copyrightable aspects of a work.