This is a simple carriage which works with magnetic ball joints and Delrin or POM wheels.  You can get the wheels inexpensively from DeltaPrintr.comThis works nicely with my magnetic effector:  https://www.youmagine.com/designs/kossel-plus-magnetic-effectorAnd with my magnetic ball joint rod ends:https://www.youmagine.com/designs/magnetic-ball-joint-rod-endsIt is based on my more universal Kossel carriage:https://www.youmagine.com/designs/improved-kossel-carriage-for-deltaprintr-or-graber-wheels-and-1515...Contact me at haydn.huntley@gmail.com if you need an inexpensive source for the ball studs and/or magnets.2014-08-17:  Slightly improved the design.  Added a lip to better trigger the endstop switches.  Made the ball stud nut traps shallower.  Changed the angle for the ball studs from 30° to 45° to optimize the amount of freedom they offer.