When you sew the seam to join the sections together, stop where the two line become one in the center about 1/4 from the edge. Leave it unsewn, so it can form a 'circle' underneath and not bunch up. Will take a picture of the back side of my Alaska block so you can get a visual of what I am saying. The last seam that joins the two parts together, you do sew that one, but make sure the other points twirl and do not bunched up in sewing it together.