This is a model of a windmill inspired by the seadraggin model (2612517) of the main blade structure. I added a hole for a 608 bearing in that structure so it would spin nicely. I also sunk it just a bit so the blades would print more successfully. There is also a bearing in the top structure so the top turns as well. So you'll need two 608 bearings to complete this.

I printed at .24 layer height and 100% infill for most items - except the engine.

I designed it so it wouldn't require any supports. The tower prints in pieces and then you glue them together. The bottom four pieces print upside down.