Bassna remixed thruit00's cooling vent, and disabled the left side. Good! I don't have a left extruder on my FlashForge 95% of the time, so this works well. BUT, Bassna left some extra mass on the part (womp-womp, I'm always trying to save on gantry weight), as well as a tiny vent still pushing air to the unused side (tsk!).
Nice thing about thingiverse, I don't have to whine, request a remix, wait for a V2.45, whatever. Just remodel and share.
So, this is a right-side-only extruder fan (mirror for left!) based on Thruit00's original design and using his clips. All air goes to right extruder and anything unnecessary is gone. Sweet!
Print in ABS, as tough/light as you can. Cheers!