Prototype 3D printed RC propeller blade, 4 3/4" overall (X2). The base is cut off leaving the 6mm X 10mm round boss which mates to the hub. The hub for 2mm and 3mm shafts and other blades are in the works and will have indexing marks to set pitch. This idea comes from WINTURER, portable wind turbine battery charger, by adriancubas on Instructables. ASA filament is recommended. Photo is PLA.

Thumbnail shows the propeller inverted. Flip and print it on its base. Print two blades at the same time to avoid overheating.