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 thingiverse.com/tag:bic


180 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 youtu.be/rWfps0nxLuI The end of the video shows that the caps also mate with Lego small ball joint parts.

Here's a simple molecular modeling program written in OPENscad. It's a derivative of the OPENscad program in "Protein Models". It contains two modules, "atom" and "bond". A call to atom makes a sphere and a call to bond makes a cylinder. Atom requires a radius and a set of atomic coordinates; bond requires two sets of atomic coordinates. For example to make a water molecule we could write:

atom (.3, 0, 0, 0); // an Oxygen at the origin, .3 for its radius
atom (.25, -.96, 0, 0); // for the first H atom, .25 for its radius
atom (.25, .24, .93, 0); // for the second H atom
bond (0,0,0,-.96,0,0); // for the first O-H bond
bond (0,0,0,.24,.93.0); // for the second o-H bond

To render it all together the above commands are included within a union statement. More details in makewater.scad.

Once I had this program I began looking for coordinates of interesting molecules to print. I found a collection of fullerenes at ccl.net/cca/data/fullerenes/index.shtml Better known as "Buckyballs" you can read about the fullerenes on Wikipedia. The buckyball most discussed contains 60 carbon atoms but the coordinate collection has a range of sizes, from 20 to 540 atms.

A truncated icosohedron made from .1" acrylic sheet.

I helped build a couple of soccer robot kits this week and liked the shape of the 40mm soccer ball included with the kits. Its surface is made up of both hexagons and pentagons - a soccer ball with flat sides. After a quick google search, I found a tutorial to build up a Buckyball or more formally, a Buckminsterfullerene in honor of the architect Richard Buckminster Fuller (inventor of the Geodesic Dome). At the heart of the object is a Truncated-Icosahedron with a carbon atom attached at each of the 60 vertices (edge intersetions). The description says this is the most symmetrical molecule possible made up of 60 Carbon atoms. Who could argue with that?

The Buckyball here (less Carbon atoms) has a 40mm DIA to match the one that comes with the soccer robot as shown in the photo of the bot, the included ball and the MakerBot printed one.

Here is the tutorial URL (no affiliation):
webdesign.org/3d-graphics/tutorials/how-to-make-a-buckyball.597.html

12 5-sided polygons that fit together to form a dodecahedron. This is probably the smallest buckyball that you could realistically make. There a solid version, and a "wired version", which is way way easier to put together. This is to mess with you geometry-lovers out there.