I cut out a big section of the back of the jacket, folded it in half around the device, then traced a line with a sharpie along the bottom of the and sides of the device. Trimmed the material to size, sewed the two halves together, and then added the self adhesive velcro and sewed on the top flap, which was another piece of material from the jacket. The two stripes were already part of the original design of the jacket, I just made sure they were lined up when I sewed the sides together.
About 2 hours to complete at a relaxed pace. Should be an easy way to case any gadget if you have free time.