Builders can find plans for a working windmill at NoTechMagazine.com and PopularMechanics.com. As of 2015, both of these websites offer plans for free without a magazine subscription.
At NoTechMagazine.com, builders find a detailed plan for a working Dutch industrial windmill from the 1850s. The website includes 21 plans for five different types of Dutch windmills from that time period. Builders click on the plan they want and find a highly-detailed layout for the windmill.
PopularMechanics.com offers the plans for a miniature working wind turbine. The plans include a detailed material list and a step-by-step guide. Each of the steps includes a photograph.