This video shows how to make and use this simple, effective contraption.
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The contraption shown in the video and pictures has two hooks. You could add more hooks if you would like. It is important that they be placed so that the cord lengths and tension are identical. For three hooks, the hooks should be placed equidistant from each other at the points of an equilateral triangle. For four hooks, the hooks should be at the corners of a square.
However, you don't need 3 hooks to make a 3-strand cord. You could put one looped strand on one hook and a single unlooped strand on the other. For four strands, you could use two looped strands on two hooks.