The basic model considered the ball as being a spherical shell with isotropic material properties.
The spherical shells were to have precise and intricate patterns cut into them.
There are three big spherical shells, one inside the other.
They were overhead, at the center of the spherical shell.
It can also be applied to spherical shells with that property.
In your cosmos, you are like insects crawling around the inside of a spherical shell.
The problem was that the shell had to fall a particular way and with spherical shells this could not be guaranteed.
When the star's outer layers blow off, they form a spherical shell.
The interior structure of the Earth is layered in spherical shells, like an onion.
On the basis of size, the Dyson sphere - a spherical shell around a sun - comes about in the middle.