You can find magnet stackers on the internet. However they are usually made of plastic and brightly colored, sometimes even color coded to indicate polarity. The purpose of a stacker is that the child discover and rediscover polarity each time the stacker is used and so develop a visualization of the magnetic field. Polarity is a tactile experience. You learn it by feeling it. You figure it out every time you use it.
This design is an appropriate use of natural materials and an example of simplicity as well as isolation of sensory experience.
In addition, because there are three spindles it is an ambidextrous exercise. The side spindles serve to store the unused magnets and keep them from being scattered across a table or floor. Finally,  because there are ten magnets it is an exercise in addition. Every possible combination equals ten.