Most CD/DVD packs now come in spindles, without any cases or sleeves. I've been using this method on and off for awhile now when I needed a quick casing.
Take an ordinary sheet of 8x11 paper. Fold it in half by length and then by width (don't matter which way first).
Then lie it flat. Where the two folds meet in the center, it forms a cross shape. Place the CD/DVD, being careful not to scratch it, in the center of the page using the cross shape in the center of the page and looking through the hole of the CD/DVD to center it as best as possible. I like to use an old CD/DVD for this step.
Then firmly hold down the CD/DVD and fold in one side (long way) tight to the CD/DVD edge. Then do the same for tthe other side.
Then do the same for the top and bottom and tuck the edge of one fold into the other.
That's it.
