I looked in my closet. No sweaters I wanted to cut up. No shirts. So, off to buy felt at the craft store I went. At .29 cents each, I bought 6 navy felt sheets. And a sheet of pretty shiny black paper for .99 cents.
First, I cut the felt to fit the width of the box.
I took 3 sheets at a time (for desired thickness, you can add or subtract number of sheets) and started accordion folding them. Put it in the box (It stayed folded without any gluing.) Repeat with the next 3 sheets. (I made the folds about 1/2 inch because I wanted to leave enough room for my biggest rings to fit with the lid on.)
Then the sides looked kind of funky. You could see all the waves and folds of the felt. So, I just cut some of the pretty paper to cover the sides of the box. I chose black paper for a little bit of contrast between the navy felt. And chose to leave the front and back paper of the box a little shorter than the sides, so I could see the rings a little bit better.
Twenty minutes later...