"Most [keychain] carabiners are cheap and crappy, and at best they last a few years," says mechanical engineer A.J. Huff. In a bid to create a longer-lasting one, Huff designed this spring-free, flexure-based carabiner made from titanium:
Huff built a rig to repeatedly flex the carabiner open, and reckons that if you open it 10 times a day, it will last "at least 20 years." They're powder-coated and come in a variety of colors.