Cardboard boxes are fine, but refrigerator door bins and vegetable crisper drawers are nicer for storing things. The good ones I used here are made from clear plastic so you can see inside them easily and they don’t block light.  

Of course, they are terribly expensive to purchase for this use, but with the (lack of) quality of Kenmore /Amana refrigerators manufactured after 2004 you can find free donor components relatively frequently.   I also believe that with the addition of standard closet shelving support brackets the glass shelves from these fridges can be re-purposed into standard wall shelves.