This is the single extruder version of my extruder mount. I had purchased an extruder mount but just could not seem to get my extruder to stay true when printing. I really like the linear bearing on the unit since they didn't need to be zip tied into place, and I also like that the belt tension stays tight and is mounted directly to the bottom bearing.

In order to make this work, you will want to have the following item first.
Reprap Prusa i3 3D Printer Parts X Axis Printing Head X Metal Extruder Carriage
http://www.ebay.com/itm/Reprap-Prusa-i3-3D-Printer-Parts-X-Axis-Printing-Head-X-Metal-Exturder-Carriage-/401045514813?hash=item5d602cea3d

You can also purchase a set of linear bearing based on the dimension that I have provided in the attached PDF file.

Good Luck!