Radiating line work.
Draw a circle around the pin-wheel a few inches from the center - still under the pin-wheel but not all the way under it. Use your ruler to draw radiating lines. Make the lines come off the edge of the circle at a slant - don't pull them straight off the circles edge. This will give a slight spinning motion. If you took the lines straight off the circle it would look more like a radiating sun.
I might even make the lines so two lines were close together (1/2"?) then a larger space, the two 1/2" spaced lines - etc.
Not sure if I explained this well.