# Penny Pincher

More than 4 thousand binder clips and 2 thousand pennies assemble in this hulking form based on the lattice structure of diamonds.

Designed and constructed in May–October, 2014.

A different view, nearly along an axis of 3-fold symmetry

Closeup view of 6-fold and 7-fold spirals

A total of 4344 binder clips pinch \$21.72 worth of pennies with no additional adhesive or support in this 35lb architectural feat.

The animation below captures the three-dimensional structure better than I was able to with static images. I initially was not sure whether Penny Pincher would be strong enough to support its own weight, and the accompanying in-progress shots demonstrate my incremental, empirical quest to find out.

This animation (made from a video, not a computer rendering) highlights the sculpture's 3D form.

In progress: just one tunnel

More progress; a 4-way juncture

Even more progress: two junctures connected by a tunnel

Yet another progress shot: almost there!

Photo taken by Will Schwartz

At a larger scale, the surface branches according to the molecular lattice found in diamonds (a.k.a., the face-centered cubic lattice): each four-way juncture locates a carbon atom, with tunnels representing the bonds. This demonstrates only a piece of a repeating, infinite structure, but alas, I don't have that many binder clips!

At the smaller scale, six- and seven-sided spirals of binder clips (as in this image above) swirl their way around the surface. Most places on this surface curve in two opposite directions, like a Pringles chip or a horse's saddle (in other words, they have negative Gaussian curvature), thanks to the 7-sided spirals. These 7-spirals are evenly spaced according to the vertices of the {3,7} Regular Gott Pseudopolyhedron, a repeating surface built from equilateral triangles coming together 7 at a time, as illustrated here.

Viewed differently, this surface can be imagined as a mildly stretched version of the Schwarz D Minimal Surface, where the "D" appropriately stands for "Diamond".