It is actually simple. I can not state specifically as I have not seen the schematics but basically you would have the design painted with Electro luminescent paint or dye. That glows in accordance with the strength of the electric current that passed though it the more current the brighter. The current is controlled by a variable resistor in this case the resistor is controlled by a compass needle and not a knob, or solid state circuits that serve the same purpose. turn the rug until the resistor is lined up with the north pole and you get the brightest glow. That is the direction the design is printed. turn any other direction and the glow lessens down to no glow.
Looking at the pictures I suspect it is operated by small button batteries.
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