On the inner astral plane thought power replaces mechanical power. One of the aspects of astral-plane life is the manner in which environments can be built.

C.C.Zain
"On the physical plane people now build mechanical robots capable of doing a marvelous variety of human work. They do just what they are instructed to do, but possess no other ability or intelligence.

That is, such a robot can be created by thought-power to possess a particular kind of intelligence and activity capability... on the astral plane the concentrated thought of many people holding the same mental image can create a whole environment of any particular kind, peopled by such robots.

These thought-form robots have no souls, no more than have the mechanical robots of the physical plane. But they act with apparent intelligence and perform the functions with which they have been endowed by the imaginations of their creators."

People with strong beliefs can build heavens and hells.

"Thus a complete heaven, according to the old Christian plan, with streets of gold, with precious jewels, with a great white throne, and angels around it playing on harps, and even Jehovah sitting on this magnificent chair as an earthly king might sit, can be created by the thought-power of a group of devotees.

And Jehovah thus created, will talk like a human being and render judgements such as these obsolete conceptions demand; and the angels will flap their wings as they fly, because they have been patterned in the mind somewhat after the manner of birds of flight.