Several authors have recently exhibited the focusing activity in the domain of so-called electromagnetic lenses. These lenses are parallel-plate layers of metamaterials whose properties can be described in terms of negative index of refraction. Known works on this subject refer to 2D structures. This work is our first attempt to show the focusing effect by a parallel-plate layer of a 3D metamaterial, whose approximate analytical model was suggested before. The mini-band of propagation and the field distribution across the focal spot are in qualitative agreement with this previous theory.