The Curvish structure of the 8 has a lot away of the stitching of a Baseball or the lines on a Tennisball. In mathematics this curve falls roughly in the section of "Constant Curvature Curves" one can find a lot of information on this curve on the website of professor Palais et al and their program 3D-XplorMath that can be downloade for free at http://3D-XplorMath.org/index.html. The image below is made with this program and there is even the possibility to view it in 3D if you have a pair anaglyph glasses. http://virtualmathmuseum.org/SpaceCurves/constant_curvature/constant_curvature.html
Daren Scot Wilson on how he contructed the seam on a baseball
Winston Mitchell made the loop like I did, by using half circles
Paul Bourke
