If you, or someone you know, shops at a warehouse store like Costco or Sam's Club, check out the free produce shipping boxes. They are very sturdy cardboard, and have these tabs on the top that interlock with the box on top so the stack really nicely. They also have a larger size but I get the smaller ones, which are about 13 X 15 X 4. The height is variable, depending on the item shipped. they seem to be standardized so boxes from different growers still match. these are big enough for all your fabric for a bed quilt, and you can lay a 12.5X12.5 unfinished block in it so they don't get wrinkled.