I would draw the design full size on paper. Graft paper if you can find it , if not, the gridded easel pads would work. It would give squares to follow. I then would draw the dahlia circle the finished size. You will then have the pattern or template for the outer edge or four corners. Then add seam allowance to the corner section. Divide the outer edge at the top center and side center. This will make it easier to cut the 4pieces from your fabric.i would use the center that was cut out to mark the pieced center in order to make sure it is a good circle and will fit the outer sections.