The trouble is that people's fingers come in so many shapes and sizes, and change size so much throughout the day, that without the big knuckle to hold it on (per a normal ring) it would be really hard to get a good fit like that. My suggestion is to sew these into come cheap gloves. They'll be easy to take on and off, and easy to keep track of.
That said, if you're absolutely set on something specific, we can work together on a solution. What I made here was just more affordable to print, fits everyone, and doesn't matter which hand it's used on. But I made it one way, I can make it another.