Now add your corners inside on the rectangle. You will only be able to make two corners in the innermost part of the rectangle.

Join the knot lines around the outside of both the rectangles, as shown. Again, there should be no ends left unjoined.

Pick a place where the lines criss-cross, and erase it so one passes over the other. Erase the other four criss-crosses so that the over/unders alternate. If you want to be notified via e-mail when new Tutorials are up and running, sign up here!