The hull

Behind the meadow is a dark layer a few metres thick. It holds the world together, stores its energy and writes its gravity. The inside gets the anime look; the hull doesn't. It is dark and grainy, lit only by light that leaks through from the meadow and by the droids' lamps.

These four pictures come from the second Midjourney hull round. Three were edited in Paper, two so they agree with the story and the physics and one for a more dramatic approach. Each can flip back to its original. They run from the outside in.

From outside

A black sphere in grey-green space with one lit square hatch on its curve; a tiny craft dives in toward it from the upper left, trailing a thin streak of thruster light. — **d2-1** · edited in Paper

A black sphere about 200 m across, with one lit hatch and a small craft coming in to it. The hatch is the only door.

In the original the craft just holds station beside the sphere. The edit has it dive in toward the hatch from high on the left, still tiny, with a thin trail of thruster light. A second edit has it skimming low over the skin instead, its lamp lighting the black surface under it.

It is black because the skin keeps almost all the light that lands on it. At Earth's distance from the Sun that is about 41 MW. Nothing can keep light for ever, though: the energy runs the Lantern, ends up as heat and has to leave as heat. A black ball at that distance settles at about 5 °C and glows only in the infrared, near 10 µm. To the eye it is the darkest thing in its sky.

The window

Looking up from inside a dark structure at a huge round window full of stars, with a row of thin struts below. — **c3-3** · as it came

The one window in the skin, seen from inside the hull, with the struts that hold it below. Nothing here turns, so the stars stand still. It is the only place in the world where you can see out, and nobody on the meadow can see it, since the ground is in the way.

The prompt asked for the hub of a spinning wheel. Here it reads as a window instead.

Under the meadow

In near darkness, a curved row of still ribs with thin lines of pale light between them; a small droid holds on in an alcove of the dark wall. — **c2-1** · edited in Paper

The ribs that carry the meadow, seen from below, with daylight leaking through the seams between them. A droid holds on in an alcove of the outer wall.

In the original the ribs are smeared sideways, because that round was written for a hull that spins. Ours doesn't, so the edit makes them stand still and leaves the rest alone.

Down here there is no weight. The ground carries a compression that exactly cancels the tension in the air above it (see Making gravity), so nothing pulls below it. The droids hold on, clip to rails and push off.

A panel lifted out

From the dark hull, a round opening framed by trusses shows the far meadow of the inside world with paths and tiny figures; below it hangs a large dark sphere above a row of silhouetted machines. — **c6-3** · edited in Paper

A meadow panel lifted out, seen from the hull. Through the hole you look across the hollow at the far meadow, 196 m away. That ground faces the centre, so from here it looks like an aerial view, paths and players included.

The original shows blue sky and cumulus clouds. Cumulus need kilometres of rising air, and this world is 196 m across, so the edit swaps them for the far meadow and keeps the trusses, the sphere and the silhouettes. The opening is the one place where the hull's darkness and the inside's colour meet.

The dark sphere is open. One reading: a spare Lantern, kept unlit in the hull.

What the hull is

It doesn't spin. The Midjourney round was written for a spinning world, after NASA's 1975 settlement study. Ours has skin gravity, held by the hull as a layer of tension (Making gravity): the same everywhere on the ground, and fading with height. Spin at this size would mean 4.5 turns a minute and weightless poles. Running at 10 m/s, you'd also be pushed sideways with 43% of your weight. So nothing in these pictures turns.
It is weightless inside. The ground's compression cancels the air's tension, so the field the hull holds stops at the ground.
It keeps spare ground. Half a sphere's worth of charged panels lies folded against the outer skin. They unfold when the world morphs, so any shape up to 1.5 times the sphere's ground area keeps the meadow's 22 m/s² (Any shape).
From outside, it has weight. In anything that stands still, tension has to be matched by compression, and the outer skin carries the other half. So the world weighs what its energy weighs: about 4.7×10¹⁵ kg with the spare ground. On the outer skin you'd feel about 32 m/s², more than the meadow's 22.
It shares the meadow's air. The black outer skin holds the atmosphere, so a panel can be lifted without losing any. At this size, about 4 cm of steel holds one atmosphere with a factor of two to spare.
It is black and lukewarm. It intercepts about 41 MW at Earth's distance and gives all of it back as infrared at about 5 °C.
It lights the inside through the Lantern. Spread over the 120,700 m² of meadow, 41 MW is about 340 W/m², roughly a third of noon sunlight on Earth. The hull itself gets only what leaks through the seams.
It was charged by its builders. The field's tension, the frame that holds it and the spare ground store about 4.2×10³² J, about 13 days of the Sun's entire output. A yard draws about 1/14,000 of the Sun for five centuries to build one (Building a world). The skin's own 41 MW runs the Lantern and the upkeep.