Well, the whole thing has been basically done for a while now.  Perhaps I should post something.

Here is a short video of the planetary transmission used to drive the cables for each of the axis.

The outer surface here is the spool for the cables.  The planetary transmission allows me to use a larger  spool diameter and still have an acceptable drive ratio for the stepper.

Three of these units are mounted on the end effector, which hangs from cables and sports a 300W auger driven 1.75mm output print head made from a large lag bolt and some pipe.