I re-use the standard size fabric bolts from the fabric store, I get 4 little bolts out of them. The price is right and so far (after 5 years) I haven't seen any issues with acid in the cardboard. In my opinion, the only people who are so gung-ho for purchasing the plastic boards are the ones who make them! I get the acid thing, but really, any damage would be minimal so I'm not worried about it, and it certainly doesn't justify my spending tons of money on fabric storage when there are other low cost storage methods that will enable me to spend that money on more fabric!