This is probably not a new idea, but I just had it, and a quick google search doesn’t reveal anything like that, and since I don’t have a 3D printer or any skill in 3D modelling, I’m posting it here, maybe it will inspire someone.
The idea is very simple, a ring, with an MX-compatible stem where the eye would normally be. You can put any key cap on it, to show it off, including those fancy artisanal ones. Could be printed, but then could be also cast from a variety of materials.
That’s it.