I started printing out a blade from the plans but stopped when I realized the twist was opposite that of a regular propeller. The tip has a greater angle of attack than the root, which makes sense for a wind turbine with air pushing on it. Learned something new. If the airfoil was symmetrical it wouldn't matter but it has a pronounced under camber. I tried mirroring it but that duplicates the twist. It also has a sharp trailing edge which is difficult to print. I'm going to start from scratch.