The classic archamedial spiral..  This is part of a wind harvesting project in the works.. 

Print is hard built with supports. The bottom wall supports are easy to remove by slicing along the seam of the propeller and support top with a sharp knife. score a couple times and it comes off cleanly. 

Printed in PLA 5%infill , 90m/s. (you can print stronger pending your use case) 

designed for use with 608 bearings.  press in bearing to front support, insert the spiral, then press in rear bearing into support and onto spiral shaft.