Cool, sounds like fun. Are you going to sell or share them?
src:
http://www.ipo.gov.uk/copy.htmCopyright protects written, theatrical, musical and artistic works as well as film, book layouts, sound recordings, and broadcasts. Copyright is an automatic right, which means you don't have to apply for it.
Which would suggest that as far as the UK is concerned your pattern would be covered by copyright without any form of registration or even needing a copyright notice displayed on the document. Personally I think it's probably best to put a notice on there so people are clear, but generally they should assume the work is copyright even if it displays nothing. Generally it's a good idea to publish the work somewhere where a date of publication is recorded so that if someone takes your work you can prove prior art. I've heard people sometimes post their document to themselves recorded delivery and don't open the envelope as the date of posting can be used to prove prior art. Don't quote me on that though. The trouble is that some countries interpret copyright differently and some don't recognise it at all, so if you think that may be an issue you should probably look at attaching a specific written license to your work.
For sharing you might want to take a look at the creative commons licenses here:
http://creativecommons.org/choose/They are frequently used for patterns that people want to share but protect themselves from someone else profiting from their IP or passing it off as their own amongst other things. Generally all you have to do is add something like "This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License." or one of the other relevant licenses to the document. The page above is a very simple form that will help you choose the right license.