This is a guard for the bottom of 24oz Contigo water bottles. I found my bottles being easily dented over time, and modified the file below from 32oz to 24oz along with a few small changes. I printed it in 95a TPU, which allows for a snug friction fit and some cushioning when dropped or set down hard. Non-flexible filaments might work, but you may need to slightly upsize the model first.

https://www.printables.com/en/model/295506-contigo-water-bottle-bumper-guardsleeve-32-oz