Love the cooler idea! I’m going to look up how to make them.
Link to the cooler adapter I used:
https://www.amazon.com/gp/product/B01N4QWRDT/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1
Video for how to use:
Note that if you use small round coolers like I did, you will want a thicker washer (Home Depot, plumbing dept.) than they provide so it seals tight (due to curvature of cooler), and I would suggest using a bit of silicon sealant, too. These worked extremely well, I made 3 of them! (Just don't forget to drill small vent holes in the lid.)
If you have a small flock and don't need a lot of nipples, this one works very well, also, and is easy - peasey. I did use one of these as a back-up waterer with one of my groups. I used this on a 2 qt. cooler that fit nicely in my chicken tractor. If you use this, make sure that you get a small cooler with a flip-top lid for drinking...so it vents, or plan on drilling a small vent hole, so water will flow.)
https://www.amazon.com/gp/product/B07TXK71J5/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1