make Trefoil Knot in MatrixGold and Rhino6
Much as the disk is obviously a Seifert surface associated to the trivial knot, one could think of obtaining a Seifert surface associated to the trefoil knot by joining each point of a curve to the farthest point of the curve by a segment line. However, the surface obtained in none other than the Moebius strip with 3 half-twists, which is not orientable.