The Challenge: Build yourself a wobbler. Wobblers are 2 circle (or 2 ellipse!) constructions that have a constant center of mass. Or rather, a center of mass that doesn’t move up and down as the wobbler rolls. Thus, resulting in a satisfyingly continuous “wobble”.
Materials Needed: cardboard, ruler, boxcutter or scissors
I first heard about this from Matt Parker’s “Things to Make and Do in the 4th Dimension”, (which is an excellent read for anyone interested, and the link above even has some printable templates for both a circular and an elliptical wobbler) – he attributes this to A.T Stewart in 1966.
To build, cut out 2 congruent circles from cardboard (or something cardboard like).
Then cut a slit that is ~29.3% the length of the radius in each circle, and use that to connect.