This is a remix of this cooling duct, adapted to the custom X axis carriage for mounting an e3D hotend.
It's not the ideal solution this hotend and carriage deserve, but it's a start. Print just as you would the original version. If you want to attach this to the back end of the carriage instead of the front (for whatever reason... you'd bump into the Z gantry while homing axes though), you'll need to mirror it accordingly.
You might need to scale it up by a factor of 10, due to me getting confused in blender coordinate systems. It was designed in mm units, so don't rescale to inches.