Celtic knots, Part 3

I first discovered Celtic knots almost 20 years ago. Since then, I´ve enjoyed working with them in a wide variety of art media. My passion for Celtic knots has even prompted me to write about them, which is one of the reasons why this column is special: it´s part three of my first three-part column, my first column of the third millennium, and it´s concerned with how to build 3D Celtic knots. I think there´s a pattern here.