PVC is light but not that light...and...bearings are nowhere "friction-free" enough to allow it to coast long enough to useful.
Honest, it was a "lark", spur-of-the-moment, idea (ha,ha), which I was 'hinting-at/reinforcing' when I referenced the Jack-O-Lantern analogy.
Anyway, now that it's been publicly published, it is PUBLIC DOMAIN, so feel free to use / develop / exploit / market at will.
ADDENDUM - You've piqued my curiosity enough that I submitted an inquiry to an INDIA "turbine vent" manufacturing website to see what they suggest!