I have written about the one-sheet menko before. As well as being an interesting structure for a valentine greeting, or serving as the smallest compartment in a Zhen Xian Bao/Chinese Thread Book, it can be used as a CD case.
The only drawback is that you need quite a large sheet of paper or lightweight cardstock. (I would use the latter if I planned to mail the CD.) The surface area of the paper provides a large space for text and images, should you wish to have either or both of those, and the menko is a sturdy container when closed.
To fit a standard CD, your paper square needs to measure 37 cm/14.5in on a side. Here’s the crease pattern.
You can find step-by-step folding instructions on my Valentine post from 2015.
If you want to read more about the history of the menko or puzzle purse, there’s a short post on David Mitchell’s website, Origami Heaven.
Jam tarts tomorrow!