This winter (2020/21) I did crochet a load of these soap savers. I used the instruction by smarticular. You can find one in English by seaching "crocheting soap saver".
The soap saver is simply supposed to dry the soap in after usage. I fand that practically especially for hair soap bars. But clearly on road in holiday it is not bad to be able to pack and take it away at any time without having to wrap the soap bar in toilet paper or tissues, 'cause it is still wet. My advise: Do not let it dry directly in your shower cabin, but in a dry place :)
You may also use the soap saver excellenty for saving soap residue you would have thrown away otherwise. I definitely have a hard time figuring out what to do with the residues and having them dissappearing somewhere in the back of the cabinet.
Have fun copying!
This blog post is the English version of @postwachstum/seifensaeckchen-zum-trocknen-und-fuer-seifenreste by
@postwachstum
@degrowth