In one sentence, describe what the following article is about:

If you want to make up a simple sleeve to keep a CD in that you can design by hand, all you need is a piece of paper, some glue, and some good folding. It's easy, if you've got a ruler or a CD for a guide. All you've got to do is:  Fold a sheet of US letter-sized, or A4 sized paper horizontally, leaving a 1-inch (2.5 cm) overlap. Fold in both sides approximately 1.75 inches (4.5 cm) inward. Open the paper flat and re-fold the two vertical side strips, then slide the CD into the pocket of the longer side, beneath the vertical side strips. Refold over the horizontal and fold in the 1-inch (2.5 cm) overlap to complete the square. Tuck the overlap into the remaining pocket and press flat. After you create the pocket, it's a good idea to secure it to make sure the CD will stay up and won't fall apart when you give it away to someone. Good options are usually staples, glue, or even just tape. Use the same method described in the previous section, using old pictures or drawings to decorate the outside of the CD case as normal. It's usually a good idea to remove the CD from the sleeve while you're doing this, so you don't have to worry about messing it up with glue or ink. One cool idea is actually designing the paper before you fold it, making the image wrap around the outside of the case. It can make the case look unique, if you don't know where the folds are going to be in each one. One little hack for securing your DIY CD cases is to take the pages from one of those old CD books people used to carry around in their cars, pre-iPods, and carefully cut the pockets out to use for security. You can even use these and just slip CD-sized track lists into the same pocket for a quick alternative.

Summary:
Use plain paper to fold a sleeve. Secure the folds with staples or glue. Design the sleeves accordingly. Slip into a plastic slip case for protection.