S-Lon looks beautiful in micro macramé designs, but it's very light, small, and more difficult to work with than traditional macramé materials such as hemp. Knotting tweezers help, along with folding the cord in half when feeding the end through a knot.
Use less cord than suggested in the blog article (or other projects with larger cord).
Glue the end knots to keep them in place.
Separating the ends of the cord with a needle makes a nice tassel.