In the DS9 episode "Far Beyond the Stars", Sisko experiences a vision, induced by the Prophets, in which he is a struggling science fiction short story writer named Benny Russell, living in 1950s America. In the vision, Benny works for a sci-fi periodical titled Incredible Tales.
The magazine's resident illustrator Roy Rittenhouse (played by J.G. Hertzler, the actor who usually plays General Martok) brings in a folio of drawings to inspire the next round of stories. Benny takes immediately to this one,
which was captioned "USAF DS/9". He subsequently writes a story with the title "Deep Space Nine" — later retitled "Far Beyond the Stars" — about a space station in the future. A conflict with the editor ensues because the space station's commander is not white.
Out-of-universe, does an actual copy of the story exist in some form? Was it ever written up or fleshed out by anyone?
Both Memory Alpha and Beta have articles about the story, including a cover for the issue of Incredible Tales that the story was intended for,
but neither article indicates whether the story had ever been written up by someone, either by the episode writers themselves or within a subsequent Star Trek novel. I would even be interested to know if it has appeared as fanfic.