[2009-03-16] Big bouncing baby blue Buckyball
![Lengths of blue plastic conduit and 3/4 in. PVC pipe tees make up this geodesic buckyball model.](../img/sphere_1.jpg)
A few times in my experiments with creative reuse I've had some very satisfying Aha! moments. One of these was my independent discovery of the now widely-known fact that many disposable soda bottle caps will fit the threads of a standard medium-base lightbulb. Another was my finding, back in 2004, that this flexible blue plastic conduit (or "ENT" = Electrical Nonmetallic Tubing), which I find very beautiful, fits perfectly into 3/4" PVC pipe fittings. Using only conduit, 3/4" PVC tees, and PVC cement, I was able to construct the giant bouncing blue buckyball model shown above. It is slightly more than three feet in diameter and bounces delightfully when dropped on the floor.
![This blue electrical conduit is cheaply available in 3/4](../img/blue_ENT.jpg)
Its construction led to the realization, on my part, that any geodesic system could be approximated by a construction toy having three-way connections and flexible members. Although many geodesic graphs call for nodes with greater than three-way connectivity, any such connection can be approximated by a circle constructed only using three-way connections, as shown below. In fact, my blue sphere wasn't undertaken with the intent of modelling a buckyball, rather it was an approximation of an icosahedron in which each 5-way joint was replaced by a 5-prong circle. I only realized after the fact that this method incidentally modelled C60 buckminsterfullerene.
![The trick of approximating a node of any multiplicity with a circle having the same number of branches, but requiring only 3-way connections.](../img/5-way_joint_equivalence.jpg)
Reader idyllthyme sent in these photos of a sphere he made using this method. He covered it with aluminum foil and used it to wrap a gift for a friend's son's birthday. He left a small port open in one side so James could climb inside to retrieve his present. Makes me wish I were child-size again!
![idyllthyme's sphere, covered in foil.](../img/idyllthyme_foil_buckyball.jpg)
![View through the access port reveals underlayer of brown paper.](../img/idyllthyme_foil_buckyball_access_port.jpg)
![The goodie-bag suspended inside the sphere.](../img/idyllthyme_foil_buckyball_creamy_filling.jpg)
last modified 2009-04-14