This is joint work with Henry Segerman (www.shapeways.com/shops/henryseg). It models a regular space-filling tessellation of hyperbolic space (one of four with finite cells). In this case, the cell is a icosahedron, and the model is cell-centered. Three icosahedra meet at every edge, and twelve icosahedra meet at every vertex. For more details, see Coxeter's paper, "Regular Honeycombs in Hyperbolic Space"