Sandwich this between your fan and mount for more concentrated and laminar airflow. This is about as aerodynamic as I could get it. The plate is 7mm thick and the cone is 20mm dia and protrudes another 13mm. The holes are 3mm. I printed one and it actually works well. One is adjusted for a .4mm nozzle, the other is for .2mm. This video inspired this thing https://www.youtube.com/watch?v=rDq4KSlZcTo&t=124s Happy Printing! The 30mm fans have a 15mm cone diameter, are 5.25mm thich, and the cone protrudes 9.75mm.
High Compression fans are for situations with airflow restrictions. For the Ducts I recommend using screws that protrude past your fan up to 5mm and adding a non permanent adhesive, like glue stick, in the holes to secure it. The ducts will likely require supports on the sides during printing.