How to sew a Hyperbolic Blanket
Mathematician and sculptor Helaman Ferguson invented this design for a hyperbolic blanket. His original construction was a poncho.
Ferguson kindly loaned me his poncho so that I could use it in a lecture and — better still — reverse-engineer it to make a hyperbolic blanket of my own. If you want to make one too, follow the instructions and photos below. Compared to older paper-and-scissors constructions of hyperbolic surfaces, Ferguson’s design
spreads the curvature across the whole surface (details below) rather than concentrating it at the corners,
shows the straight lines (geodesics) clearly, along the seams where different colored pentagons meet, and
is a joy to hold in your hands!
To make a blanket, you’ll cut lots of pentagons from a sheet of fleece and then sew them together.
How to make the template
The template for the pentagon is too big to fit onto a single sheet of 8.5" × 11" printer paper, so you’ll need to print the left half and the right half onto separate sheets of paper
and then carefully tape them together.
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