"You have a favorite designer. Scratch that, you have 15 favorite designers, and you show your love by stitching every pattern they publish, sell, or teach. But then comes the truest test of your loyalty; What you do with other people's designs has the bower to both wow and wound. Learn to respect the line between adoring your favorite designers and infringing on their copyright."I highly recommend that you read through the article and also read Stacy's blog about the response she has received here.
When you take a class the instructor/designer is giving you permission to make the piece for your own personal use. This is the same for projects in books.
You can not teach the project to your friends or teach other classes, photocopy the instructions or sell the design or finished goods as your own.
Bead&Button has a whole selection of downloadable pdf's on copyright here. You can read "The Beader's Ethics", "Know Your Rights to Jewelry Design" and "The inside scoop on what it takes to be published in the magazine".
Stacy also writes for BeadStyle where there is a great blog on the issue of copyright and bridal jewelry here. That said, most designers are happy to hear from people who love their work and want to a) teach a class based on their design or b) sell their finished work at local shows. All you have to do is ask....