When you rinse out your growler there's still a fair amount of water left in it and upright it takes forever to dry. Turn it upside down and mine are unwieldy, likely to fall over and break as soon as the family pet walks past.
To get around this I made a stand so it sits stable. All the water will drain out in about an hour. After that turn it upright, leave it open and it'll dry completely overnight, ready for the next fill.
If you have a smaller growler like the second picture just scale the geometry to the size of the opening before printing and it should work just as well. The original is 40mm which fits the 45-46mm inside diameter growlers I have. Leaving a couple five mm of slop so the fit isn't too tight is recommended.
Notes:
A food safe material like PLA would probably be a good idea.
