So once I had my straight needles, crochet hook and stitch holders etc organised, I started wondering how to cope with circular needles.
The solution was almost the same as for the straights, with a bit of an internal redesign so that the pockets faced inwards and there was space for a needle gauge. Each pocket will hold up to three circular needles comfortably (depending on needle size).
The only problem was that this case didn't really roll up very well. Eventually I figured out that the best option was to fold it in half and concertina it, holding it all in place with a loop of elastic round a button as before.
I'm not as pleased with this case as I was with the one for straights, I'm sure with a bit more reworking I could improve the way it folds up and closes, but it works and has been in use ever since I made it.