Where can one get that kinda chain for the wallet?
Hmmm... honestly probably Etsy. Or look for local art shows or conventions that would have vendors. You are searching for chainmail jewelry or chain maille jewelery.
Mine was made as a 16 inch necklace as I purchased it. I had the seller add some smaller rings to each end and remove her necklace hardware so I could add my own hardware. It is titanium. I added sterling silver hardware from ebay for my own use.