How to build a windmill - https://news.ycombinator.com/item?id=4579932 - Sept 2012 (53 comments)
also:
How to build a windmill part 2: Parts, nuts, bolts and blades (2012) - https://news.ycombinator.com/item?id=10791461 - Dec 2015 (7 comments)
How to Build a Windmill, Part 2: Parts, Nuts, Bolts and Blades - https://news.ycombinator.com/item?id=4584772 - Sept 2012 (10 comments)