I'm not a lawyer, and I only know what most people know about copyright law, which isn't much. However, I've been making quilts for the Alzheimer's Art Quilt Initiative and I often see the work of others that I'd like to use in one of those quilts. I've had really good luck simply asking permission to use something I see. Most people are very gracious and the internet makes it simple to track people down. It's irritating to have to do so, I know, but I don't begrudge designers getting paid for their work either. Everyone needs to make a living somehow. I'm not particularly artistic or imaginative and so I'm happy to pay designers for their work. If I want to copy something, I just ask. Most people give their permission readily. And if they don't, then I decide whether they'll get any more of my money in the form of purchasing their patterns.