Step 2: Plan layout
In the end this design 'limitation' allowed me to include a mouse mat area. For the accessory storage requirement I'm going to attach a stretchy material to the long flap (what is the underside in this image). So, the long flap can go both under the short flaps for a tidy looking case, but along the outside of the snap/velcro short flaps if you're carrying extras. I'm going to head over to tj-maxx and pick up a nylon sports shirt with a nice pattern and adhere it to the outside.