My husband and I got a kindle last Christmas and have loved using it. It came with a fantastic leather case, and we used it all the time. About a month ago my husband won another one from his school. This one didn't come with a case. I figured it would be way more fun to make a case for myself than for him, so he took the leather case.
I didn't have any stiff interfacing, but I did have lots of iron-on fleece. I used iron-on fleece on both the outside fabric and the lining, so it has lots of cushioning.
I really love the outside fabric. I got a small piece from Joann's about a year ago and couldn't decide what to do with it. Luckily, I only used a little of my small piece, so I can use it again. I added some quilting to the front to highlight the cool design. I free-hand stitched it on my machine with the foot removed.