The waterbottles on my zoozones rattle terribly and when the hamsters decide to chew on them, the sound is horrendous! The hamsters live in my bedroom. so you can imagine what a lovely outcome that is!
I was awake one night (rattling wasn't allowing me to sleep) when I had an idea.
The next day, I took some thick cardboard, like that on delivery boxes, cut it into a small square then pierced a hole with a pencil. I slid the water nozzle through the hole, then reattatched the bottle.
It reduced the noise greatly and actually seemed to discourage one of my hamsters from gnawing his bottle!