Right-left arrow keys rotate the small gear (15 or 30 teeth). Up-down arrow keys rotate the large gear (60 teeth). Space moves the small gear inside or outside the large gear. Press 1 for 30-tooth small gear; press 2 for 15-tooth small gear. C changes the backdrop color. T activates the "tracker," which highlights one tooth on the small gear. (This is the only element not made with the pen).
Now it is 100% Pen!!!
