R.
One of the best things I've seen for this was a book and some shoelaces that came together in the package. Each shoelace was divided into two colors, so when you made the loop, that end was a contrasting color from the other one you would wrap around it. The Book was instructional, but I'm sure you could just do the same thing with regular laces and fabric paint or dip them like easter eggs into some food coloring or Rit dye.