Super simple and yet kind of cool.  You need a machine screw, a wing nut, some scrap wood about 4″x.5″,  and some stretchy elastic.  Directions and Files Here.  Check the video on Twitter to see how it moves. Article from American Mathematical Association here.

Also if you don’t want to make from scratch, we could send you the parts.  Fill out this form – no charge, but we may not get them to everyone if there is a crazy amount of interest.