This wallet was made by my daughter, she is now studying leather crafts and do me an experiment, I have no idea how she design it nor I have given recommendation. I post this instructable in reverse engineering aspect, with a simple plan you can understand.
Step 1: The Plan
I think the plan not larger than an A4 size, the wallet is made with 4 piece of leather sheets stitched together as shown, the first piece is the back piece opened a square hole to insert the key ring stripe, the stripe end is cut a triangle shape to prevent it drop out, the keys bundle can pull back into wallet and staple with button.
The 2nd piece is the middle piece fold back to front as the coin cover also stapled with buttons, the 3rd piece is the front piece of the coin wallet with both corners folded to give a volume to hold coins. The 4th piece is the key ring stripe to hold an ordinary key ring, the length of the stripe must be fully pull back the key bundle.
Step 2: Stitch All Pieces
Sorry I don't know how to do stitch, my daughter knew it, may be later, leather piece is still expensive.