Make a Switch Knot: Knot Making Tutorial
Step 1: Pull the fillers apart, so that there is a gap in between them.
Step 2: Bring each knotter over each filler so that they now lie in between the filler cords. The fillers have now become the knotters, and the knotters have become the fillers. (This switching of the cords is the actual SW)
Step 3: To secure your SW, make an SK about 3/4″ down from the last tied bit. This leaves a bit of a gap and forms the lacy look.
Step 4: Tug on the fillers a bit so that the lacy bits look even.
Try this: Using two different colored cords, and a 2 SK, 1 SW repeating pattern, you can make a sennit that looks lik this: