I made a guitar strap from our expired 3" NHRA approved seat belts. It's really comfortable, looks bad a$$ and my guitar teacher wants one for his banjo. Mine has the metal pull down adjuster from the shoulder harness, of course it needs to be plastic. My question is, I just melted the button hole for the posts to slip through and am sure they willl loosen with time. Any ideas on clip on posts or a way to improve the ends?