The one ring to rule them all. This model was based on this image, using MATLAB R2016a to make the "height map" of the inscription on a toroid instead of a sphere, unlike most of the models I've made by this way. I tried to follow the proportions of the ring from the Lord of the Rings (LotR) and The Hobbit films. The files have different inner diameter, from 9 to 24 mm. All of them are the same file scaled to fit to the inner diameter. It is also included a 9cm diameter ring if you want to use it as a bracelet.
Check out this amazing pure gold casting of this model, made by AlumiTube: https://www.youtube.com/watch?v=Ndh4W-YT6oA
Update: all the models were changed following standard sizes from here. You can check this to find the equivalent for the different size conventions. Since the new Thingiverse GUI is buggy, the download links could be broken, so I will left the links in a list here for the files with their inner diameter to simplify:

I spend part of my time making these models, letting them available and free for everyone. If you want to support my work, you can contribute with me here:

Found 32 3D-models for “r o” across many websites

Stark Ice Scrapper

Cyvasse

Inn at the Prancing Pony Sign

My Precious - The One Ring - Amazon Alexa Dot Cover (Gen 1 / Gen 2)

One Ring

Orc Emergence

Toys R Us Logo HD

CYVASSE - Base boards Hex and 10x10 and individual tiles + game rules.

The One Ring RPG Dice V1

Llavero J.R.R. Tolkien

Hexagon map of Middle Earth

Boxes of Calibration R_E_R_F