By George Hart for the Museum of Mathematics


A string hyperboloid can be made by running strings between two circles and rotating one relative to the other. Here’s one large enough to stand inside of—it is fourteen feet high—between four-foot diameter circles.

It is easy to make your own. Just cut out two circles from a sheet of plywood, drill a series of equally spaced holes, and be prepared to tie lots of knots.

See all of George Hart’s Math Monday columns