How we made a better countdown/spindown die, inspired by sphericons. Countdown d24: https://www.mathartfun.com/thedicelab.com/CountdownD24.html Thanks to Alexandre Muñiz for the idea to make a countdown die based on a sphericon. My article on Rolling Acrobatic Apparatus: https://www.ams.org/journals/notices/202107/rnoti-p1106.pdf You can 3D print your own sphericon and three-cone sphericon: https://www.printables.com/model/177077-sphericon https://www.printables.com/model/177213-three-cone-sphericon