You'll need to use 3mm drill bit to drill holes throuh the lower el_h fan mount holes. I used M3 screws to mount the extra part to el_h.
OpenSCAd sources here: https://github.com/spegelius/3DModels/tree/master/ARTME_3D_Filament_Extruder_remix
The author remixed this model.
Extra part for mounting additional fan to el_h part.