For making hydropower in the river or creek, you could dam it up if need with larger rocks and put this infront when its not a rainy month where debres could fly into it though it should handle it ok. this could very easily could make 5 volts probably more like 12 when fully submersed and geared for the torque. I made the holes for 1/4 inch threadrod but wire would be ideal for this aswell so I may release another version for wire cable still.

could be sized to fit into a tube and have a wide inlet to funnel more pressure. also the z can be scaled down to spin faster.

unprinted and untested. I might actually suggest going with the 2754011 thing and trying to add more generators to it.

Hydroarc3 is only 3 inches tall I'm hoping it will print in a reasonable ammount of time and still be rigid enough. The circular print rings on bottom are for removing after print has finished.

Hydroarc4 and 5 are just tests for now. not for printing ziptie the plastic sheets cut from pop bottles onto the center. i think 100mm x 150 mm should be large enough to make something work. looks like i used 75 x 5 instead of 72 for the angles hopefully it spins ok still. says 1 hour print time for hydroarc4.

Hydroarc 7 says 4 hours and hydroarc 7large 7 hours. considerable time reduction from the more detailed first versions.

Be sure to smooth corners to make it fish safe.

Would say this makes 20-50 watts but probably more like 150 - 200.

https://www.ebay.ca/itm/FreeEnergy-12V-24V-DC-Permanent-Magnet-Motor-Generator-for-Wind-Turbine-PMA-350W/132083425769 motor like this should work good for generating. there are cheeper options though.

https://www.ebay.ca/itm/new-Micro-wind-turbines-generator-small-DC-motor-blades-DIY-kit-LED/312472817077

https://www.ebay.ca/itm/Mini-Micro-Small-3-phase-Wind-Turbines-Hand-Alternator-Generator-3V-24v-12v-New/282101871316 , other project claimed this was about 5 volts 0.2amps

Updates:
was able to print v3 of this took 8 hours, next time I would like to print v7 to see performance difference and 4 hour print time.

made 4 motor version of the generator , still untested, might use thrust bearings instead also might need to thicken the base and add rope attachments. gears line up but might be off center a littlebit, v2 is ready hopefully that is fixed

Other Good Ideas

https://www.thingiverse.com/thing:2754011 could make a generator such as this one. or print a simple gearbox to up the rpm for 1/4 inch threadrod version.

https://www.google.com/search?q=Natural+Wood+Wind+Spinner

https://www.thingiverse.com/thing:11640 another good idea for using blinds to make a large surface area water wheel. zipties/hotglue might work good to hold blinds on

https://www.thingiverse.com/thing:3616584 found this too