Update 2018-04-21: Added two additional versions
I had no idea what this was for when I uploaded it. I didn't think it would be useful for anything other than as a 3D print demo, I just made it to satisfy my curiosity. But if you check out comments below, guttyr discovered you can spin it up by blowing on it, and it can be used by speech therapists to help special needs kids get better at breath support and control.
Different parts of the spinner will spin depending where you blow on it, I'm still figuring which locations and angles work best. Maybe it'll help me too as I'm frequently out of breath when I'm at altitude or underwater.
It can be printed with a 0.5mm extrusion width and 2 perimeters without infill.