Update: minor adjustment to fan bracket so there is a little overhang to help guide air. Will need supports on print.
Since getting parts from Infimech seems difficult, and they aren't listing the aux fan anymore, I took matters into my own hands. Will want tree supports for blower section with 50 degree overhang. I used a little gaffers tape to seal between fan and base. Plugs into left side of electronics cover at noted port.
uses 120 x 120 blower fan like this one
The author marked this model as their own original creation.