Back-engineered from a discovered Spindle artefact, this immense piece of engineering is used to convert raw energy and anything else it can feed into the hopper into the very stuff of planets.
Given a good mixer who can program the mind-bogglingly complex on-board computer, a Strata-machine can build anything you like, from a mile-high cliff to an idyllic sandy beach.
Of course, once the thrill of driving one wears off, the operators have been known to introduce unauthorized personal signatures, like a dinosaur fossil clutching an "End Nuclear Testing Now!" placard, or a pair of boots several miles down in a supposedly millions-year old coal layer.
This is invariably detected by the Company, and retribution inevitably follows. Of course, the actual punishment is administered by a Sec-Exec such as Kin Arad, who did the same sort of thing when she was a young S-machine operator herself, and knows when to go easy.
Strata was published in 1981. Two years earlier, the Hitch-hiker's Guide to the Galaxy first aired on BBC radio. The radio series was novelized and committed to LP record in 1980. A theme of h2g2 is the planet Magrathea, where the local Company built custom-made planets, including a planetary outer skin to disguise the fact that the utterly insignificant little blue-green planet Earth was in fact a super-computer designed to work out the Question to the Answer which is 42. For more: go here
What Slartibartfast could have done with a Strata-machine, as regards fjords and other crinkly bits...
Cross-fertilization of ideas, between Terry Pratchett and Douglas Adams?