Or maybe it is not a mod since I started from scratch. At any rate this is a decent story and about making tools.
So the other day one of the girls at work wanted to do hands on blacksmithing (basically you pay $5 and you get to pound a piece of metal), and she wanted to make a bottle opener. The slight problem being I had never made one, but said sure because I own more then I care to count and therefore line make one. So I worked out a design and how to make it. The design was a flat taper that curves around. Basically my thought was of the slim projection on a SAK opener. Is was a beautiful elegant solution, and I was able to take her through it. But beauty often seduces us on the way to truth.
The next day I decide to make another one as a sample, I wanted to test it out. So, after finally finding bottles with caps, I tested it and the hook bent. Given that I don't generally drink out of that kind of bottle, I underestimated the strength of a bottle cap and over estimated the steel I was working with.
So the next chance I got I tried making two other designs one of which a simple flattened out hook worked the treat.