Bottle caps are like people, some of them are really stubborn. This is one of the general types of adjustable cap wrench (usually for the disabled or elderly people.) It's got a little wedge for opening soda cans as well. I made this for my mom who has lower vision due to her age, so it's in bright pink.Print with 100% infill should work fine. Grab with your palm(see photo), not just with your fingers. It'll make it even easier.