it depends on whether or not they are using a commercial pattern or teaching a 'technique' if it is a 'technique' class you can use the technique to create anything you want- and sell it; if it's a commercial pattern you should contact the show, or the designer and ask for permission. it is always a controversy, with lots of opinions- many people think you *should* be able to sell anything you make----but; there have been situations where people have found themselves in trouble- including fines- for selling without permission- it is an easy thing to send an email to the show and ask- once you know what their policy is *and have the response in writing* you can continue on...some always say yes...and remember- if you do have permission to sell your item made with a commercial pattern you should always include the designer information on the label (designed by) *give credit where credit is due* .... never hurts to ask- sometimes can hurt to not ask.