Cilíndrico ambiguo ilusión círculo cuadrado impreso en 3D squarcle ilusión óptica
The Squarcle (A 3D Optical Illusion) by PhilKloppers - Creative Commons. Not suitable for children under the age of 3. Avoid leaving the part in direct sunlight as it could start to soften. 8.05 x 8.46 x 2 cm.