Two Versions of a Celtic Knot

The knot is a derivative of the one described in thing:2217022. That knot's path is a continuous line. It was modified to make a knot with a closed path. The result is a Celtic knot with seven crossings - see 7 sub 4 in - https://en.wikipedia.org/wiki/List_of_prime_knots and also - www.maths.ed.ac.uk/~aar/knots/celtic.pdf (p. 43.) The openSCAD code makes version one of this knot: celtic_ver1.stl.

D. Moews felt that a version of the knot with smooth curves would be more attractive. He sent