It’s called a cardbow. It’s in the same vein as the minimalist wallets but but is unique in that it uses a composite spring instead of elastics and metal.
There are way more pictures on the campaign page.
https://www.kickstarter.com/projects/1106663250/cardbow-perfectly-hold-the-perfect-amount-of-cards
I’ll answer any questions I can about the layup and processing of the spring. Which was all done in house.