Problem: All the caps that came with the 48oz glass bottles I was using for kombucha fermentation / storage had worn out and did not hold pressure any more.
Solution: Kombucha Kaп! Cap works great on the bottles I tested it on (pictured) and holds pressure. Plugs should be printed out of TPU (or similar material) since you'll never get them into the caps otherwise (and I don't think they'd do much good for pressurization if made out of a rigid material). They're small enough I don't think much of the print settings are going to matter as long as your walls are set high enough (I used 5 walls and 20% infill). Supports are recommended for threads.
Caps with integrated plugs are there just because I could. I don't know if they are really worth the length of time it takes to print an entire cap and plug out of TPU considering the length of time the threads will probably last.
I tested numerous different sizes of plug diameter and got them to where they work great for me but I have no idea if they will print differently for anyone else so please let me know your results.
The author marked this model as their own original creation.