I’m not saying a rubber band like you put around a group of objects, but the sort of thing you can buy in a spool or by the yard at a craft store. Usually it’s like a thick string of rubberized fabric that you can make an arm or leg cuff with.
Hemp would be listed as twine or cord usually, and is in the jewelry making section in most stores. You can get large amounts of hemp twine at some hardware type stores, but it’s usually a bit more unsightly.
I literally bought an entire cart of sparkly white cotton yarn for .67 cents per roll, I have a 110 quart bin stuffed full of it in my attic somewhere, one day I plan to use it lol (there’s probably squirrels living in it) You never know what you’ll find at joanns haha.
For cheap yarns, the cotton ones as well as others come out in holiday collections every year, and half of those end up in bargain bins in joanns, michaels, etc, by January. Christmas often has whites, reds, greens, silver, that can easily be used for other projects.
Easter too.
Just something you can add that costs you very little, but someone would see a lot of value in. Like a bit of extra catnip, a string or rubber length to hang them, just something that someone could get from you that they would want, but wouldn’t want to have to go out and buy, so they’re...
I’m an avid crocheter, and I haven’t had cats in a while, but previously I found that they get their claws stuck in yarn items easily once it’s a bit frayed. I think they’re incredibly cute, and a great idea, but I would look into types of yarn less likely to fray when clawed. If you have cats...