"Stronger" Kossel Carriage with integrated belt clips for open belts

This is a slightly modified version of the great "Kossel Carriage with integrated belt clips for open belts" (http://www.thingiverse.com/thing:221667)

* Balls are jointed to the grip
* removed hole on the center that weaken top grip

Edit: This has been obsoleted by my other version https://www.thingiverse.com/thing:4694728