Old and tried method of protecting your intellectual copyright is to mail a copy to yourself by registered mail, and file all the unopened envelopes. On the outside of the envelope you write a detailed description of what's inside, to be sure you can lay your hands on the right envelope in the event of a court case! I have registered envelopes going back 10 years, as I was badly stung by someone producing casts from my work and selling them. Also, before making a presentation of design ideas to companies I do the 'sending it to myself' thing as well, as once people have heard an idea they frequently think that they've come up with the idea themselves, or that "it's so simple that anyone could have thought of it". I always let people know that I'm doing that, to bring home to them the fact that ideas are intellectual copyright.