The Half Stepper

This mod eliminates the second extruder assembly on a FlashForge Creator-X. It re-uses the cooling fan from the missing extruder to blow air on the print nozzle via a duct from the top. The only new hardware you will need is screws to hold the fan down in it's new location, and two small nuts that should come in your spare parts bag to insert into the slots on each side of the main body. There are slots on each side of the main body to slide in a pair of nuts (should have come in your FF extras bag) to tighten it up against the aluminum mount rail. This uses the original stepper screws. The stepper on the right will need the screws shortened to 20mm, or to be replaced with 20mm screws.
The mod attempts to:
Lighten the moving assembly (minimize stress, vibration, wear)
Eliminate failed prints caused by the second nozzle interference
Improve print resolution and quality by maximizing solidification as PLA exits the nozzle
Simplify extruder maintenance, and improve access during maintenance
Provide better support for the filament guide tube
May also work on corresponding Flashforge and MakerBot models, but no promises.

More interesting info here:
http://open3dp.me.washington.edu/2014/11/flashforge-creator-x-reducing-mass-improving-build-quality/