There is the same issue with embroidery designs, but with them you are simply limited to how many items you may sell at one time with that particular design.
Copyright stuff, like Disney, is a little different. But the general school of thought is, once the copyrighted item is offered up for sale, and it's purchased, the purchaser then has the right to use that item as they see fit, and this includes creating and selling a finished product. By selling the product, the copywriter has, in effect, waived his right over control.
One pattern I have, Through My Window from Patch Works, has a very explicit policy - they ask that you contact them regarding selling their design once made. If you ask permission, what they do is just limit how many you can offer at time, like no more than 5. It's a pretty intricate design, I can't imagine anyone making more than 5 to sell.
When I have items with copyrighted designs for sale, I always carry a disclaimer with me in case somebody asks. I've never had to show it.