The GEB models are a tribute to the shapes featured on the cover of Douglas Hofstadter's book "Gödel, Escher, Bach: An Eternal Golden Braid". These "trip-lets" come in two different shapes for the upper and the lower position and in three sizes. High-resolution pictures can be found at http://flic.kr/p/5StVjJ, http://flic.kr/p/5TfkzR, and http://flic.kr/p/5WdB79. This particular one is the lower piece and with 4x4x4 cm the large size. Its counterpart is http://www.shapeways.com/model/13421/g_e_b_upper__4x4x4_.html.