You can use cotton or cotton lycra for the top, those are most common but there's so many options! Velour or performance pique are good too. For the inner you'll want an absorbent material like bamboo fleece, but flannel can be used if you can't order bamboo online. Then a waterproof layer (PUL) for the backing, and optional is another backing layer outside the PUL to stop slipping
I use bamboo fleece (or bamboo French Terry more so now) and I've never been able to find it in store, I an in NZ though. I buy mine from Greenbeans NZ, but they have international websites too!
I put the fluffier side of the bamboo against the cotton topper as I find it gives a bit more grip while sewing. And yes I have my website with some ready made ones 😊 youandfynnnz.myshopify.com/?_ab=0&_fd=0&_sc=1
I use bamboo fleece (or bamboo French Terry more so now) and I've never been able to find it in store, I an in NZ though. I buy mine from Greenbeans NZ, but they have international websites too!