I got tired of all these fan holders that were either an entire case, or were meant for fans larger than 40mm. So, I took the opportunity to create a very simple and basic fan holder for the Sanguino. Check out the pictures, they will tell you everything you need to know. I positioned the best part of the airflow directly over the Z-axis stepper drivers, because the Z-stepper driver tends to overheat the quickest because it has to drive 2 motors instead of one on my Reprap Air 2. I hope this is of any use for others. Printed this on 0.25mm layer height, you are free to do what you want, but this layer height is fine for me because of the thicknesses in the part are mostly round figures height-wise. The parts are both placed in the STL ready-to-print.