I have been wanting to make myself one of these for ages. My interchangeable needles are all over the place and I badly needed something to store them in. As this was a try out, I used fabric that I didn't like very much in case it didn't turn out. I now need to make one in funkier fabric.
There are pockets for the needles themselves, with tape that I can write on to indicate what size needle is in the pocket. I think I have made too many pockets but no matter, I can always have more of the same size. Also three large pockets for the cables, my tape measure, sewing up needles, row markers etc. Three smaller pockets for for the needle stoppers and the turny thing for getting the needles on to and off the cables.
It folds into three and rolls up and is secured with ties to that nothing falls out! I'm really surprised at how well this has turned out. I used paper to make a pattern using the needles and cables to make sure I had the right size. I must make another one in prettier fabric. The fabric I used was Fabric Freedom William Morris designs.