Sturdy keychain quick-release buckle

**Latest model (with minor enhancements) is available over at MakerWorld:** https://makerworld.com/en/models/490300

I really like mistertech's qucik disconnect keychain design, but found that every now and then it would detach while in my pocket or while being removed from my pocket. As a result I almost lost some important items several times.

This design occupies almost exactly the same overall dimensions (size comparison in pics), but is virtually impossible to detach accidentally. Like a typical side-release buckle, it has two arms that must both be disengaged at the same time to detach. I took care to design it so that even if one arm is released and the entire thing is jiggled it still won't detach.

The tradeoff is that it's a bit harder to attach and release than mistertech's design. I find it easiest to put the female part on the keyring I want to detach, then use the my fingertips/fingernails to release the arms while pulling down/away on whatever is attached to tha