I don't like CD racks. Fitting the CD/DVD into slots all the time, and then the racks themselves fall over and get in the way. So I decided that I want to keep my audio CDs in a bookshelf, where they'd be out of the way and stable, but easy to view and grab.
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.
Pic 2 is two cases about to be connected. The outer edges of one will fit over the inside edges of the other.
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.
To add strength and to make the unit hold its shape I needed a back.
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.
Pic 4 shows the current state of my collection. In the back you can make out the un-glued support structures for the big stacks, and in the front are the glued ones with backs for boxes to put in front of the other stacks.