I made an approximately 15" border on a circle table topper. You have to cut it out in wedges. I then sewed all the wedges together and ended up with a unit that looked like a giant donut. I then carefully pinned and attached to my center. It came out really nice and flat but I was really concerned while drafting it. Here are pictures:
http://www.quiltingboard.com/picture...r-t189285.html
If you look carefully you can see my seam lines in the border.