This design is remix of this model contains bearing for ease of rotation. You need 3x 6700zz bearing.

This model has better & smoother rotating performance. I strongly recommend this version. But if you don't have bearing, check this model:

ASSEMBLY

It's very easy to assemble.

1.) Put bearings to inner and outer  toroidal propeller.

2.) Assembly last bearing to hub

3.) Then take the hub (orange) and put outer toroidal (yellow), washer (grey), inner toroidal (purple) and sun (yellow) respectively as shown.

4.) Now, stick the rod to bearing 

5.) As final step, you can use this clamp to attach your windmill.