How many balls?
The picture shows what happens when you put just one ball in a kaleidoscope, which corresponds to the symmetry group of a cube. The 48 balls that you can see correspond to the 48 elements of the symmetry group of the cube.
The underlying cube helps you to realize more easily how the balls are "organized" in six rings of eight balls each (corresponding to the faces of the cube).
You can see an analogous photo in the same kaleidoscope; or the photo of an analogous situation in a different kaleidoscope.
From the exhibition Simmetria, giochi di specchi - Symmetry, playing with mirrors.