Here are two icosahedral pencil holders. They were constructed by replacing the triangular faces of an icosahedron with triangular motifs like those in thing 75045 - Desk Ornaments. The topmost face of the icosahedron was deleted and a prism added to the base. Stl files are: icosa_holder_4.stl icosa_holder_12b.stl and the openSCAD code is: icosa_holder.scad. Both files can be printed directly on the build surface. Nice prints were produced by my Replicator without the need for support. I used two shells, 10% infill and the prints weighed about 25 grams.