I think thatâs possible, though very difficult. The reason we use physical bodies to make physical bodies is the intense amount of energy that goes into building one.
This is easier, youâre non physical and an energy being so you can fiddle with peopleâs energy to give them thoughts, if they allow you to. Or you can find mediums and people with psychic skills and just talk to them as fellow spirits and their conscious mind gets the message passed on from the subconscious.
Depends what you mean by âvoidâ. 
I would say not, as itâs not possible to be âinâ the void. If you are, itâs not void any more by definition, now itâs a space with you in it.
After you die, in my worldview all that happens is you shed the human body and still remain in the universe. Some traditions believe you automatically reincarnate, some that you hang out in an underworld thatâs separated from the rest of the universe.
So supposing this is the same thing you meant, regardless of what itâs called, here you are, a sentient energy being that is discarnate in some way (and there are I think many levels of non physical being as well, depending on what bodies you retain and your ascension).
You want to manifest a human style physical body on Earth, like a full tulpa?
One the way Iâve heard of it done is you build your astral or light body here on earth, taking advantage of the powerhouse thatâs a human body to build up the required energy. I think this is the same thing as âbuilding your shen or spiritâ that is the gal in qigong.
With a prebuilt astral body you can practice manifesting that while alive in astral projections that other humans can see, then touch. If you can do that you should keep that after shedding the physical.
Another way Iâve read, in the âLife and Teaching of the Eastern Mastersâ books, is the body itself is transformed into a light body.
Itâs not something youâll get a hard answer on, just opinions, like the above, as we donât remember anything before being human to be sure.
I think if I could have just manifested a body, without losing my memories, I would have done that rather than take a physical incarnation in the first place. Such a body looks as you wish and is disease free and immortal.
So it seems difficult to learn once discarnate. I suspect the whole point of physical evolution has been to create physical bodies that have the senses and abilities and permanence (without constantly maintaining the manifestation) we have, and can be ascended to this level of multi dimensional being. This is why some say humans are âdna royaltyâ. It may have been felt thatâs itâs easier to start with the base and raise it up that start discarnate and build down.