Math Monday: Pencil Star

by George Hart



We’ve seen mathematical pencil constructions in past Math Mondays columns. (Why go to the hardware store to buy dowels with all those shiny pencils just sitting there in the office supply cabinet waiting for someone to make things with them?) Here’s a lovely new design by Cory Poole. It is a five-pointed star assembled from eighty pencils.There are five identical 16-pencil units around a central axis. Two units are shown below, before assembling. Each has the form of a hyperbolic paraboloid based on a four-edge cycle from a regular tetrahedron.If you’d like to make your own, Cory provides step-by-step construction instructions.




This article first appeared on Make: Online, May 2, 2011.

Return to Math Monday Archive.