If anyone is REALLY interested in building their own windmill, I will send you my precision engineered 10 foot diam blades from mine - for shipping cost and a few cases of beer! Was a double set of 3 blades, one set behind the other set for super high efficiency, from about a 1980 Popular Science magazine. Aerospace aluminum to fiberglass blades. They worked great! I can't throw them in the trash! Direct drive a simple AC motor or DC pm for batteries.