This is a pen cap with connecting features to make geometric shapes including a truncated icosahedron. This item was inspired by other pen cap items on Thingiverse http://www.thingiverse.com/tag:bic180 pen cap parts assembled make a "BICky ball" (AKA: truncated icosahedron, bucky ball, c60 and buckminsterfullerene)60 pen cap parts assembled make a dodecahedron. (The last two pictures show the dodecahedrons)The large "BICky ball" was not able to support itself so I had to build it with something to support it on the bottom. (the support is an upside down mini-trampoline covered with a sheet)I uploaded a video of the shapes and the connectors to YouTube http://youtu.be/rWfps0nxLuI The end of the video shows that the caps also mate with Lego small ball joint parts.I used a CNC mill to make aluminum molds and injection molded polypropylene to make this part. I had to use two separate removable insert in the mold to form the cavities in the cap for the pen and connecting feature. I cut the aluminum molds with a 1/16 end mill.