A variant of gripping gears (https://www.youtube.com/watch?v=ENFXnNtd3xU) adds holes so that a solid object can pass through the connection between the gears. 3D Print files at Thingiverse: https://www.thingiverse.com/thing:3908970 This video was filmed during ICERM's Fall 2019 "Illustrating Mathematics" program, which was made possible through the support of - The National Science Foundation (Grant Number DMS-1439786) - The Alfred P. Sloan Foundation (Grant Number G-2019-11406) - A Simons Foundation Targeted Grant to Institutes (Award ID 546235)