Outline for story "Hitch-hiker"
Start with a character who has the resources to do almost anything he wants - Elon Musk/Richard Branson.
Give him the motivation to do something - Dying of cancer(?) - Iron Man Marvel, but also Black Sabbath Song.
Story
Character has interest in space travel. Discovers that he has x. Decides he would like to "go out with a bang".
At the same time, new comet is identified inbound from the edge of the solar system.
Character decides to marshal his considerable resources because he wants to see the edge of the solar system.
Spacecraft slingshots around sun to catch comet on the outbound journey.
Character lands on comet with limited material but with "3d printer" and lots of designs and uses the comet as raw material.
He builds a reasonable home. A comet nucleus could quite reasonably be an 8 km sphere. As much surface area as a reasonable small island.
You can borrow ideas from "Silent Running", "2001" etc.
Maybe he finds something interesting out in the Kuiper Belt or Oort Cloud.
https://en.wikipedia.org/wiki/Elon_Musk
https://en.wikipedia.org/wiki/Richard_Branson
https://en.wikipedia.org/wiki/Iron_Man
https://en.wikipedia.org/wiki/Iron_Man_(song)
https://en.wikipedia.org/wiki/Rosetta_(spacecraft)
https://en.wikipedia.org/wiki/Kuiper_belt
https://en.wikipedia.org/wiki/Oort_cloud
https://en.wikipedia.org/wiki/Halley%27s_Comet
https://en.wikipedia.org/wiki/Comet#Long_period
