turbine meter

Print two of the body and one fan.
Put the fan on a pin, mount it in front of a HY860N photo_interrupter. Maybe put another on the back. Put a slotted disk in the middle of the HY860N.

Weld the two halves together. I thought about putting flanges on the halves, but probably no benefit.

Uses Denise Lee's nifty turbine generator.