How someone conceives of the Cave Center will depend on a variety of factors, including their actual level of growth and development, and where they really live within their persona.
The Cave is often described as an etheric organ located in the third ventricle, in center of the head, near to the pineal gland. However, associating the Cave with a particular location is problematic, as it is a state of consciousness which is not limited by time and place, or to a location.
On the experiential side, a heart-center type will tend to conceive of the Cave in mystical terms, while a throat center type will tend to conceive of the Cave in occult terms. Both would actually be either preparing for or working on the integration of the Ajna rather than the Cave.
At this point, most of the students of this material have some of both "some heart center and some throat center development" but do not yet actually have a fully functional Ajna (although they may well believe that they do).
The Cave is usually described as "near" the pineal, because it does not have a precise location. The effective location will vary somewhat, depending on the frequency held by the consciousness, and the strength and quality of the intersecting magnetic fields of the Crown, Ajna, and Throat centers.
The Cave is built by placing oneself in the center of the head, becoming aware of and as the integrated persona (human soul), becoming aware of and as the Spiritual Soul, and merging those states of awareness into one. Of course, in order to begin this building process one must both have an integrated persona, and be able to align and identify with the Spiritual Soul.
Some of the most important parts of the process of building the Cave, are the intent to do so and the placement in the Cave. If someone is not able to identify as the Soul, focus an Intent, and place their awareness in the Cave, then they are not ready to begin the building process. They need more work with the lower centers (which is true of most students who reach the first Cave Center technique in The Nature of The Soul [link to WI NS page] course, as many have not had adequate preparation prior to the course, and/or have not been doing the assigned techniques up to that point).
Another crucial (and even more neglected) factor is that the Cave, being the "place where magic is done" is developed through the actual practice of The Magic of Consciousness.[1] One cannot develop the Cave simply by placing onself there. One must actually and active use that placement to manifest some portion of the Divine Plan through the conscious practice of the inner creative process.
With all of the above in mind, this is where the "proceed as if" principle becomes quite important. One places one’s awareness in the center of the head and hold it there (thereby producing a magnetic field of tension) and proceed as if one were actually holding a Cave Focus, aligning up with the Overshadowing Intent, invoking it downward, moving it out into appearance, and aligning whatever appears back up with the overshadowing Intent. This is the basic process one uses with any Divine Energy, or overshadowing Purpose, Awareness, or Intelligence.
During the day, one places oneself in the center of the head and thinks "I" . The regular practice of this simply identification will help accustom the incarnate self to this placement, and via that placement eventually develop the magnetic field and focus of consciousness in the Cave.
Now, all of this makes sense when and as one actually achieves a Cave Center focus of consciousness. At that point, one does not experience the Cave as a location in an individual physical-dense instrument, but as a state of consciousness within the instrument of humanity.
This is one of those things which, when described, is only a pale reflection of the reality (and please to not add glamour to my words. It eventually becomes as mundane as, say, driving a car). But there is actually, in a sense, only one consciousness or self, and only one Cave, which appears in many places in time and space. Thus, as one develops the Cave, one can, as the Conscious Soul incarnate, move as identity from Cave to Cave.
However, in this context "movement" is not the correct term, for one does not actually go anywhere, one merely adjusts the frequency, quality, and focus of the consciousness in the Cave.
Unlike the other centers, the Cave is a state or activity of consciousness, not of the form. Thus, its life is not tied to the cyclic activity of substance, and once built it does not pass out of incarnation with the rest of the persona instrument.
So, when one moves into the Cave, what has moved is the consciousness, and not into a physical location (which is merely a convenient reference point) but into a state of consciousness. So, when one is in truly in the cave, one is identified as the consciousness or Soul in a particular state of being.
Now, imagine we were discussing radio waves, and that moving into the Cave involved tuning into a particular frequency of those waves. It’s the same frequency for everyone.
In that sense, moving into the Cave is a "tuning in" to a universal state of awareness, and from that state one can go up to higher states, and/or out to include a broader number of "stations" . In fact, when working from the Cave, one does both. One works throughout as a group unit within an even larger group life. How large depending on the one’s capacity and the work to be done.
[1] See: The Nature of The Soul, lessons 28 through 35, and my article on that subject