wrote in message

actually those are the ones that I don't want. What I'm
referring to is pretty much a symmetrical unit and there's
no axle to the wheel. It just sits in the housing and
rotates however it needs to.

Only think I can think of is a roller ball with a steel ball, not rubber.
http://www.leevalley.com/wood/page.a...at=1,240,41060