Simple Metal Cable Chain Mounts
This is a remix of the extruder cable chain mount (http://www.thingiverse.com/thing:514728), and the Bottom Link of the Open Cable Chain. (http://www.thingiverse.com/thing:40918) Both of the mounts presented here have been modified to make them fit on the Simple Metal's base and extruder.
I had to tweak my y axis stop, resulting in the loss of a couple mm from the print bed's volume, otherwise homing the Y axis will result in the printer grinding as it tries to compact the chain down. YMMV.
Edit:
I've uploaded a newer version of the extruder mount to accommodate the cable exit if you've managed to do what I did and strip out the screw that the bearing screws into, forcing you to rotate the extruder motor to get a 'fresh' hole. :)
I also added the mounts for the Y axis harness; the motor side I went lo-tech/low-rent on; You'll need either a pair of zip ties or a really long skinny tie that will wrap around the motor. the lower mount has a plate that lines up with the a screw hole in the base; You'll need a screw that fits it to secure it.
Edit, 2/28/2015: Removed the 'work in progress' flag; I've been running with the current versions now for a couple months, and it's been solid.