Fermentation airlock bubble

Extremely simple and straightforward design, done within 5 or 10 minutes.
We get to used make sauerkraut in home from my childhood and want to taste that again. Even I can buy some ready-made sauerkraut in shop, it's not the same. You know... :)
Cabbage was already in bucket but I forgot to purchase air lock (we called it bubble trap).
So I designed one very quickly. It's useful for various home fermentation things like homemade wine (I loved my dad's currants wine. He mixed black and red currants and wine was amazing - heavy, sweet, color of ruby), beer, apple cider, pickles... You name it.
Enjoy it!