Hello Nick
I worked on a personal product for my company Leaf Fly Fishing Equipment. That I used a living hinge in metal for. You can see the product here on my website
It will fail over time but it is a 1000 cycles or so before it fails which is fine for my application. I ended up using a Stainless Steel alloy that was stamped and kept a very thin piece between the outer and inner plates as the hinge. It works quite well if you don’t over flex the part.