About this 3D model

An "illusion" that has been around for years, rings that roll. What else can be said? Grand kids love them. Very short garage floor video is here: http://www.youtube.com/watch?v=HLmnVpQsMtQ&list=UUv_zm49u-RjnCJVwhUO-ecA. Designed using Sketchup 8 and printed in PLA on a Replicator2 using Makerware 2.3.3.42. Printed mine at Makerware "High" resolution.