I also attempted to put an elastic around the back, this way it could be attached to a coloring book or a binder easily. The elastic I used was not quite stretchy enough, so I need to go and find some different elastic. (this is the white/blue pattern with pink zipper)
What is great about these is they are perfect for teaching my daughters (and their friends) how to sew! They each picked out some fabric big enough to cover the felt, then quilted them together. This was very forgiving as you didn't need to be straight or precise. The zipper was a big more challenging too. And it's done quickly and they have made something! They were very proud of their creations! I have their 4 cases in the picture below, as well as some of just the fabric/felt quilted together.
