you DO need permission to sell something you made with someone elses design- the patterns normally say "for personal use only" which means you can make it for your self- if you want to sell the items- or even display the items you need permission in writing to do so-
sometimes the copyright owner gives permission to sell up to 5- or 10 (some number) other times they say no-- you may not sell the item.
i just went through this with one of the quilts i made and was entering into the fair- contacted the copyright holder telling them about completing the quilt and my intensions- i received an email back from them telling me it would be ok to display the quilt (with the designer credited)but not ok for me to sell the quilt
you should always ask- make sure before trying to publicly sell another persons design- it can be a costly mistake.