Four small bearings of various sizes and one large ball bearing are trapped in a brass cylinder divided by a plate with various-sized holes through which the smaller ball bearings can pass. You need to get each ball bearing seated on the hole through which it cannot pass.

From the maker, "The largest ball will remain in the top position. All you need to do is put the remaining ball bearings on each designated spot to end up with a nice and tidy shelf. The only trouble is, you will need to guide the smaller ball bearings around each of the larger holes and make sure they don’t fall back through."