This is a very dangerous item to print. You are printing it and using on your own risk. You should have a knowledge of how 3D printer parts work. Author is not responsible for any loss, damage or harm caused by use of these propellers.
I was experimenting with 3D printer propellers that would not require any supports for printing. The mechanical strength is achieved by the print orientation alone. The blades are interlocking with the hub via dovetail.
These are very high pitch propellers designed for high speed flying. BUT I do not recommend putting them on anything with higher power than 150W.