I've used these rubbers: https://amzn.to/4dnZbLg
But these should also work: https://amzn.to/4ba8gFW
You can also use the ones with 4 rubbers and just leave one empty hole in each side (I suggest the middle one).
I printed it with PETG, but after printing and testing, most probably PLA would also work. Let me know in the comments/makes.
Print HORIZONTALLY to increase strength/resistance.