I believe 3-D printing and its implications on intellectual property is an interesting topic. Clive Thompson recently wrote a brief article on this in Wired: http://www.wired.com/design/2012/05/3-d-printing-patent-law/
For a more detailed look, please see Michael Weinberg's white paper, It Will Be Awesome if They Don't Screw it Up: 3D Printing: http://www.publicknowledge.org/it-will-be-awesome-if-they-dont-screw-it-up
I don't know of any libraries that currently make 3-D printers available but they're are fairly cheap so I could see it happening in the near future. I do know of some universities that have them in academic departments outside of the library so I think it's important that librarians have a little knowledge about them and the potential problems that could arise from their use.
Since it is still a new topic it may be better suited for an "On the Horizon"-type webinar, perhaps combined with the Augmented Reality topic.