I am looking for joint(s) small enough that I can attach four of them at one point and still have them smaller than 1cm. U-joints would be small enough but may have too much "play". Ball joints probably don't come four at a time. I've looked at a dozen ways I could build such joints from scratch (using simple elastic or springs), but they all suffer from fatigue or excessive play. Even LEGO joints are too large, although they're within a factor of two. Can anyone direct me to a source (presumably online) that has tiny parts like this, or where I can ask about tiny parts?