This application is a third wheel spiro graph. With the bars 4 seek you can control the length (l) and the number of teeth (t) of the wheels.
The formula:
                          x = l * sin (t) + I 2 * sin (t * t2) + L3 * sin (t * t 3)
                          y = l * cos (t) + I 2 * cos (T * t2) + L3 * cos (t * t 3)

If you toutch the spirograph picture the app will calculate 10000 steps. The pictures can be saved on SD card into the "Spirograph" directory