The gif is made with geogebra and [url=https://ezgif.com/]https://ezgif.com/[/url] .effects to make the border.[br][br]The seam line of the tennis ball is base on : [url=https://mathcurve.com/courbes3d.gb/couture/couture.shtml]https://mathcurve.com/courbes3d.gb/couture/couture.shtml[/url]