If I direct a breeze towards one side of it... it actually spins. If I keep fiddling with it I think I will create concave blades. I think 4 or more would be better than 3 as well. Had a piece snap off in the original top... made the sleeve to restore it's functionality... might have been a better solution anyhow.0 infill. The tabs on each fin did not print perfectly round, so I cut them off with a knife and then use a paper clip as a axle. I used a dab of gorilla super glue to hold the axles in the top and bottom. One fin fused to the bottom, but with a Stanley knife and some patience I was able to free it again.