D20 Cord Lock

My beloved backpack was built with nothing but a sleeve of leather to keep cinched tight the cord used to cinch closed the main opening. This worked fine for about two weeks, then it started to wear out and began allowing the cinch cord to slip loose and the main pocket to open. At first it took a while for the pocket to open, but eventually it began to happen in only minutes. I needed a solution. I needed a cord lock. I could buy one, I suppose, but I didn't build a 3d printer and spend years fiddling with it just to buy a generic, non-personalized, factory made, and much less of a headache inducing, cord lock. So, I scoured the internet. (I searched Thingiverse and Printables).