If you need a small 30-40 mm fan for cooling and improve quality of your 3D printings you can try this axial to radial conversion of a small fan.
Step 1: Modifying the Axial Fan
Just cut the fan as in the sketch and step one is ready. Use a very sharp cutter and be very careful...
Step 2: Convert Your Fan
Print back and front parts and glue the parts to the fan. The axial-radial fan it is ready.
Next you will print the nozzle adapter and glue to the fan. The adapter can be customized for your application.
This is it all, enjoy your new 3D printing fan.