I decided to try them to use to fold my fat quarters and keep them neat. They are thin but sturdy enough for at least a yard of fabric to be stored upright. I think I'll stack them flat since I'm folding fat quarters on them. I got 100 acid free white boards at Amazon for about $15. They were called Silver boards, I don't know what difference the color name makes, some were labeled Gold. I could have gotten them cheaper elsewhere but DH has Amazon Prime so I get two day shipping free on anything so it was cheaper there. (Check out the Prime shipping for a one time yearly fee. It saves mes lots of shipping cost) These are really nice boards to have for lots of things. Templates, school projects, tote bottoms, etc.
I have boxes of fat quarters and have no idea the best way to store them so I know what I have. I'll give this a try until I run out of shelf space.