I don't remember when I built this one. The design for this model is easy. I just took the compound of 12 cubes as shown here and added one cube according to the symmetry. Easier said or thought than done. After that I needed to caculate and to start building again. That takes several months alltogether (I don't remember how much exactly). Anyway I was very satisfied with the result.
A picture from another angle can be found here.