The sphere is approximated by 20 very thin solid cylinders. This illustrates the disk method of finding the volume of the sphere, commonly found in a Calculus II course.

This model was designed and printed by my WLU summer research student Emily Jaekle ('16). A full description of the build can be found at http://mathvis.academic.wlu.edu/2015/06/22/volumes-by-slicing-disk-method/