The natural 3D evolution of the Sexominoes, and the Polysexes in general, is this cube. The table below represents the number of cubes in function of the number of side-forms, when the forms are "simple" and symmetrical. If the order is odd, one of the side-forms is flat.

The diagram below represents the ascii notation when the order is 5. Here there is a complete ascii table of the 800 Order 5 SexCubes, which could do a 3D puzzle of 10x10x8 cubes.

Below there is an example of Order 5 SexCubes:

A modified sub-set of 27 pieces do a 3x3x3 puzzle:

This file contains the complete ascii list of the 27 sexcubes.