This is a remix of Super simple upgraded Kossel Mini effector by Laurman to be able to use steel balls with an M4 hole and magnets in the rods. Also, since the extrusions are facing away from the center, it eliminates the problem of rods catching on the fan edges, thus limiting printable area.
Hope it helps
P.S. Spacing is 45mm between centers of the holes
P.P.S. Uploaded the carriage I used here: https://www.thingiverse.com/thing:2482759
P.P.P.S. Added a Solidworks file. It is an STL-import and the remix done, so still a messy file. But should be ok for some minor adjustments.