NOTE: This was one of my first designs and it is far from being perfect. Please consider printing the new version published here http://www.thingiverse.com/thing:2054260
This is the set of 8 pieces that completely cover K8400 wires. I printed them with 0.1mm quality and "touching bed" support type.
All pieces are mounted to the existing holes with M3x10mm screws and self-locking nuts. Only one screw that is right above main controller board must be M3x8mm to fit. I used regular M3 nut there, since it is not as high as self-locking nut and I glued it with thread glue.
Pushing all wires below these covers is not an easy task; it takes a lot of patience. You will need to pull all excess wires down through the hole in the printer bottom. Start mounting covers from the top and finish with the bottom right piece. To attach the nuts that are between power supply and the bottom of the printer you either need to temporarily remove power supply, or stick nuts to the piece of blue painter's tape and try to get them under the screws.
To make sure the longest piece fits Vertex print bed, rotate it in Repetier around Z-axis for 41-42 degrees.
2 pieces with the names ending "_support.stl" are mounted from the other sides of the back and bottom panels.
I added the 2nd revision of x-motor_extr1 file that is required only if you are planning to do the following modification to your printer http://www.thingiverse.com/thing:1857266
I just published new revision of these covers: http://www.thingiverse.com/thing:2054260