You don't need a pattern for this. Just take three long strips of fabric and fasten them together on one end, then start braiding like you would when braiding hair. You will have to keep adding lengths of fabric to the strips, you would best do this by sewing them together. When you get enough length to work with, start forming it into and oval or round shape. As you do this you will have to hand sew it together so that it holds it's shape. Also use a heavy duty thread when you do this.