This is a 340mm diameter prototype VAWT that's intended to be a scalable demonstrator. It accommodates 3 blades which are stolen directly from scrap vinyl vertical blinds. (Yes, those ugly fat ones that hang) You just take the single blinds and insert them in to the slots. I put a dab of 2-part epoxy to keep them in place, but the fit is tight. The blade arms attach via 3x 3mm screws or bolts. The central hub is sized to use a 7/16 shaft (I use 1/2" threaded rod that's cut down with a lathe in just the right place so I can put a 1/2" nut below to support the turbine). Note that there's a 20-tooth gear face on the hub, if you'd like to drive a mechanism- though I doubt you'll power more than landscaping lights until this is optimized. That being said, I have included the solidworks part files so that you can change the blade angle, etc. if you'd like. Oh, and you could print more than one set and drive a multi-tiered version with really long blinds if you like!
Printed in ABS on a 12" cube reprap. Should print on anything that can accomodate at least a 140mmx140mm build surface. I set fill at about 35% for my first, and it was plenty strong.