Battlement couching is a beautiful filling stitch that can be used to create the illusion of depth by using different tones of the same color. It forms diamonds that are then couched to the fabric (More about couching).
The threads are laid in a crisscross pattern. I am going to start with the darkest. I am going to use 4 different colors. You can use any number of colors. Just make sure that you have enough space for all the colors.
The threads are not woven here. Instead they are simply laid out in one direction and then another layer is added on top in the opposite direction.
The second color is added slightly to the side of the first color.
Note how the threads crisscross. The threads will form the English letter V as shown below.
Adding the third color.
Couching the topmost layer.