Thane>I took a video of a metal version of Bill Gosper's lissajoke rolling on the floor at Bob Hearn's house ( http://gosper.org/lissajoke.gif ). Completely coincidentally, Bob Hearn is narrating its ambiguous rolling behavior as I'm pushing it around on the floor. Anyway, here is the videohttps://www.youtube.com/watch?v=7YpYCgRt9Qc&list=UUbBGpH5hVMFF23WjuaFzjcw The ambiguous rolling effect is quite noticeable when I push it farther away. ------------- rwg>Alan Adler's rejoinder suggests rpm outweighs viewing distance. And mentions something much more newsworthy: AJA>I posted the Lissajous video here http://youtu.be/Rli5x91Jg64 with this description: This is a rotating Lissajous shape designed by mathematician Bill Gosper. The shape is four inches in diameter and is rotating about its axis. Guess the orientation of the axis (either horizontal or vertical). There's a good chance that you'll guess wrong. There is another Gosper Lissajous shape here https://www.youtube.com/watch?v=7YpYCgRt9Qc I posted my 5:54 Euler disc run herehttp://youtu.be/N_bMbuEQ6wM <AJA Joe Kisenwether suggested building the object that actually does what https://www.youtube.com/watch?v=LGUfgplJRSc seems to do. NeilB figured out what he meant, and Meshlabbed it for Shapeways. Unfortunately, UPS delivered it smashed (but in an unsmashed box). Neil's dad pretty well straightened the thing with his bare hands, and on the Thanksgiving dinner table, just before we ate, Neil shot https://www.youtube.com/watch?v=M16IuOioz1k (Roller machine by Alan Adler.) --rwg