Allows use of a 1" x 1" x 1/16" aluminum angle between the top stepper motors. Use drag chain from top of Z to the "top" set of steppers. Brackets hold drag chain http://www.thingiverse.com/thing:119814 to motor mounts as shown.
Update - External bracket added. I needed an external bracket for the "chain guide hold down" end piece. I had a difficult time getting to the lower holes once multiple wires were passing through it. This works.
Infill: 25%, 2 Shells, .2mm, 30mm/s
I used supports, but it might work without.