You’ll need two folded cords, secured with
lark’s head knots, creating four cords. The two outer cords are the working cords.
Move working cord 1 over cords 2 and
3, towards the right. Pass working cord 1 under working cord 4.
Move working cord 4 to the left, passing
it under the two middle cords and over working cord 1. Pull on both working cords to tighten the knot, while holding the middle cords steady.
The two working cords have now switched
places. Move working cord 1 to the left, passing it over the middle cords and under working cord 4.
Move working cord 4 to the left, under the
middle cords and over cord 1.
Tighten the square knot by pulling on
both the working cords, while holding the two middle cords steady.