Feline Fosters: Whatcha using for litter mats???

Hey there, fine foster friends! As the title says what are you using for litter mats?

I hate clay sand litter with a burning passion. It gets everywhere. But unless I want to buy my own litter, that's what I have to work with for my rescue.

Currently, I use silicone litter mats, but their kind of a pain to store - they're bulky, and not the lightest thing.

So....what do you all have? My only requirement is that it needs to be able to hold up to washing, if washable. I take a lot of medical fosters with GI bugs, so I'd like to be ablento sanitize and reuse instead of tossing it with each litter.