Designed by Oskar van Deventer, made by Recent Toys International;
the box this one came in says copyright DaMert Co. 2005.
(plastic, each edge is 3.5 inches)
Four balls each have a number of circular depressions that allow them to be packed tightly together inside a pyramid shaped cage.
A ball can rotate only if it sits in the depressions of at least two other balls.
The goal is to rotate the balls so that each side is a single color
(red, green, blue, or yellow).
Here are the other two sides:
By observing that the green and blue faces have only one depression,
observes that a relatively simple solution proceeds by solving green and blue first
(to allow more depressions available for the remainder of the solution).
That is, position the red-green-blue corner, then the green-blue-yellow corner,
then the third planet on the blue side, and finally the remaining planet,
where the last step may require some temporary rotations of the other balls.