This simple design is a tool, that enables kids to knit knurling using seven strings of wool. Just put a knot on one end and put the strings through the center hole. That take every third string (direction does not matter) and put it over to the free slot.

You may refer to this description on how to use this tool (German): http://ringelmiez.de/2014/09/02/mein-gegenvorschlag-zu-den-loomz-armbaender-flechten-mit-einer-holzscheibe/