Orbitals were a way of providing a vast amount of living space with a minimum quantity of material. A complete Orbital was a hoop in orbit around a star, a narrow band just a few thousand kilometres wide but three million kilometres in diameter, spinning just fast enough to provide one standard gravity and a standard day-night cycle. Usually, rather than construct whole Orbitals in one operation, the Culture preferred to start with Plates; a pair of slabs of land and water (plus full retaining walls) of a couple of thousand kilometres to a side, spinning in a similar orbit, attached by tensor fields to each other, and behaving like sections of a completed Orbital. Each Plate would have its own geomorphological features designed in from the beginning, so that the super-dense Base material could be formed to the basic shapes required for seas and oceans, rolling hills and mountain ranges, canyons and craters, tundra and desert, and all the other geographies which could be found on a planet - or even structures which could not exist naturally: islands that floated in the air or on the water, for example, graced more than one Orbital, to the evident pleasure of the residents.
The actual Plate construction was performed by a bewilderingly vast array of titanic machines looking, for the most part, like a cross between floating factories and spacecraft to which an eclectic collection of arcane gadgets had been bolted. Some were essentially static, energy delivery systems (planetary crust-busting weapons, if you insisted on looking on them that way) which heated the material to form the required rocks, water, air and so on, as well as the rather more energy-expensive transformation to the exotic high-density substances that formed the strategic base material itself. To provide that raw material, other machines - closer to proper ships - intercepted asteroids, comet nuclei and other cosmic debris from around the system and re-directed these rocks and iceballs to parking orbits, initially, from where Lifter craft would tug them to the transmutation engines.
All of this frenetic activity was coordinated by one or more Minds. Right now, the Better Mousetrap and the Geomorphological Eccentricity were collaborating closely with the newly-awakened Mind, now installed in the newly-constructed Hub, which was previously known as the Pressing Matters but had now taken on the name of the Orbital. The construction machines were controlled by AIs; most were semi-slaved to one of the three Minds, with only a few independently sentient ships in the fleet.
Muevinla, of course, was in her element. As a matter of course, she had access to whole suites of design-support systems, atmosphere and water flow patterners, weather modellers, plant growth simulators, animal behaviour analysers, image visualization tools, holographic projectors, generators for sounds and smells - in short, everything she could desire to make her landscaping ideas come vividly and realistically to life.
Her productions - as flat-screen shows, walk-though holograms, immersive virtual-reality experiences and every other form of communication the Culture used for entertainment and education - were widely experienced across the Culture, being variously quoted, commented upon, criticised, demonised, applauded, deprecated, complimented, disparaged, praised, vilified and recommended, all as part of the typical Culture democratic process in deciding - well, everything, really: absolutely anything of any serious consequence and quite a lot of stuff with absolutely no consequences at all.
Her principal audience were, of course, those people on both GSVs who were considering whether to jump ship and take up residence on the new Q'aantar Orbital, once the first Plates were complete and before the great ships departed on their separate course schedules. There were well over a billion people on the ships - many of whom would have known well in advance about the new Orbital - and she would consider herself extremely pleased if a couple of percent of the population would remain.
Her total audience was not so parochial, of course. Her works had already made available all over the Greater Galaxy; her hope was that people looking for a change would pick Q'aantar as a pleasingly different place to live, even if they might not actually take up residence for years or even decades. A typical full Culture Orbital could provide comfortable living space for tens of billions of people without them ever needing to come into close proximity with one another; the prevailing Culture being that, if you wanted to live on top of millions of other people, then you should stay on a GSV.
[tight beam, M8, tra. @n4.28. 571.197]