A Spirograph is a toy from the 60s of the last century. You can draw nice flowers based on mathematical curves called hypotrochoids. This built is inspired by the Looney Gears and features an excentrical planetary gear set. I used round teeth instead of classic involute gears.
This is YACS, yet another cnc-cut spirograph. As a specialty it uses hypocycloidal (round) teeth which allows optimized machining on a cnc, as the tooldiameter has no problems on small teeth like with the sharp edges of involute gears. Furthermore I added not only holes, but three triangles on each planet gear. This results in interesting shapes. As a gearset I decided to use 48, 50 and 52 teeth for the sun gear and 39, 40 and 42 teeth for the planet. This results in 9 different rosettes: