But when you stack a number of cases on top of each other, the weight makes it difficult to extract cases from the lower areas, and even more difficult to return if you want to maintain some kind of order to your collection.
So I wanted separators; something light and thin and fairly light, like, CD cases.
These are strong enough like this to support other CDs if they are stacked in a rack. But they don't keep their shape if you move the structure at all and I wanted some to stack in front of others.
I used contact cement and glued the edges together. After doing so, I glued one on the insides of a case to one open end of the box, as in Pic 3.