Yes, I bought a phone bag, only £4.99. Its design fault is that the top and bottom of the bag is solid black so my on screen controls get obscured. I will buy another, this type totally clear, that'll work! The issue for me is not the bag, its the carry system! I do not want a lace around my neck, I want a soft supple neck strap shaped to cause minimum chaffing and can be snapped on and off easily.
While you are at it, could you please design a pair of instant snap-on hiking gaiters please. No zips, no studs that need clicking together, lugs to grip the laces and no under the boot laces or straps.
Good luck with your project.