Racing Rings consists of three rods one each of copper, aluminum and PVC, Ring magnet is dropped down the PVC rod, it falls unobstructed, Two metal rods create an induced magnetic field to that adds resistance to the rings travel, metals are different, they fall at different rates
Simple Atwood Machine, include Apparatus and 2 pulleys connected by a rod, 1.75inch plastic pulleys connected to a 3inch rod, Overall length is 8.25inch, Two pulleys are connected by a metal rod.