Abstract: Provided is a magnetic building block, in the form of a 3D polygon of non-magnetic material having at least four faces. The faces meet in sets of at least three to define at least four vertices and a generally enclosed structure, each face having an outer surface. At least one internal holder is adjacent to at least one vertex, each holder structured and arranged to receive a magnetic ball and permit free rotation of the magnetic ball. The holder positions the magnetic ball so as to be generally in about equal distance to the outer surface of at least three faces. A magnetic ball is disposed in each internal holder.