Great phone wallet design - would be easy enough to duplicate. I would eliminate the binding (since mine would be a mess, lol) and just sew a backing on RST. The zipper pouch could be the kind from Michelle Patterns Zip Pocket Pouch.
Handbags & Wallets - Learn how to sew wallets. 3 patterns included and the video tutorials show you every step of the way. Lots of great sewing tips to get the best results. - How should we combine handbags and wallets?