Circle Illusion

#### Circle Illusion, Optical Illusion

There are various optical illusions, of which the spinning circles make a worthwhile 3D design project. One has many opportunities to sketch and offset circles. The present design is just an example. It creates a dual conic illusion when spun slowly (refer to the GIF demonstration below).

The circular board has a diameter of 120 mm. The filament should be changed at about 70% completion or after the base is printed, to create the color contrast. Of course, white or light-colored filament can be used to print the whole board. Once finished, the crescent patterns can be painted using another color.

Thanks to the ** natural warping**, the board can be spun on a smooth surface without a stand. If so desired, a stand can be used to raise the board for spinning. Have fun!

####References
1. https://en.wikipedia.org/wiki/Illusion