My grandmother always used paper. She called it shelf paper and just folded it
to fit. (I actually still have it in a few pieces of furniture I got from her) But it looks like plain greyish newsprint type paper that you can buy in bulk to wrap stuff up for moving.
Thanks for the suggestions. I like the bamboo placemat idea for the shelves that "show", and material for drawers and lower shelves that will not have glass doors. I guess I can use double-sided tape to make the corners stick.