In my quest today I discovered a wheel that makes nice wm2d art by adjusting one parameter ;D.
Behold some examples...
(https://overunityarchives.com/proxy.php?request=http%3A%2F%2Fziosproject.com%2FNJ%2FartWheel.PNG&hash=03e0f68b3e21b717a101c0c7f78504e2b812a799)
The ways you can set this up are really endless seeing the ratio can be any real number. And the combinations of attaching the rods to the smaller inner wheel. Currently depending on the ratio the wheel would run at a constant speed until friction stops it or it would swing back and forth until again stopped by friction. The workings of it are not hard. I'm willing to to explain it on a very basic level if people are interested since I'm too lazy to do it spontaneously :P.
wm2d file:
http://ziosproject.com/NJ/artWheel.wm2d
have fun.