Timely synchronistic thread!
I would like to provide a perspective on it.
The Rainbow body is one you already abide in, but you use this vehicle of flesh to execute your will. When it learns enough, you move the seat of awareness from the physical, to the actual wavelengths of light/musical tones that resonate and animate the body.
So that is to say, at first these light-tones and sound-tones are crudely simulating a life, but then when they establish a fine locus of control and self-resonance, they become self-aware in a sense, and you are that. The crude simulation is experienced as a form of trial & error statistical simulation ("Life has its ups and downs", "life is suffering", etc) very much like Monte Carlo simulation which is used in engineering/physics.
What animates the body after all, are these very fundamental colours (EM waves) and tones (phonons)! So you can abide in the atomic mass, or you could abide as the fields themselves, if you will to understand.
I was actually planning today to make this very thread, admittedly nowhere near as colourful or excellent 