The back cover of this is a remix of http://www.thingiverse.com/thing:258715
I decided to put a cover over the connections to the power supply I received in the kit for the Mostly Printed CNC. I found the one above for the same power supply, but I removed the holes for the Switch, Voltmeter or Ammeter as I was not using them.
I also changed the hole size and location for the AC & DC wire, to use the Electrical Endcaps I designed instead of grommets for the holes: http://www.thingiverse.com/thing:940458 I included the openscad file for endcaps & the modified version of the P/S back. I did not change the front cover, but included the original STL file of it here. If you want the switch, voltmeter & Ammeter holes, use the original design listed above.
I included a elongated version of the Wire cap & a shorter version. I needed the longer version for the AC line, since I had stripped the outer wire further. I put crimps on the wires & needed 12v wire the same as the AC hole. You can change the Diameter of either hole to what you want in the openscad file.