I dippose, to start things off I know the internet is rife with instant gratification and the free flow of information. But some places still operate at a bit of a slower pace. There aren't always people scanning through all the posts looking for things they can contribute to. Also, not everyone who looks at the post will necessarily feel they are equipped to answer. Different people have their own specialties and areas of study ... Think of it as a lesson in patience.
On occasion some posts might slip through the cracks if left long enough, but yypically someone eventually finds it. ^_^
As for your question, the ideas behind astral travel and its relationship with form is a bit layered. Energy is seen as malleable and formless, but that form is heavily affected by your nature and psyche. So while one can feasibly just re-shape energy into different forms, in this case, changing your image and form requires changing your own nature and Self image. Easy in concept to do in short bursts, ... comparable to playing pretend I suppose. But the longer and/or more complicated the change, the more focus and effort it takes.
The overall idea to changing your appearance or other aspects of yourself while astrally travelling would be best accomplished through visualization. Using something simple for an example... Say you wanted to have a vision of protection like thickly scaled skin. Here is how I would try to make it happen;
While already in meditation and preparing to make an attempt to go astral, add a step of consciously feeling your energy/aura. Bring your awareness to as much detail as you can. How far fo you feel it radiate, does it feel soft and flowing, or dense and strong? Are there hot or cool places? Is there a shape to it already that you can feel/sense out.
Now imagine that energy shifting to a new shape. Think about how it would feel to have thick, strong skin shaped into overlapping protective shields. How big would they be? How thick? Are different areas of your body covered in different ways? Give them a color that is significant to you. Like a grounding black or a protective steely-silver. Get creative anc in depth.
Then consciously focus on the idea of your energy and aura changing to match the image and feel. And be aware of any new sensations of intuitions as well.
Then, finish your usual routine for going astral, keeping in mind the idea of taking along this new personal state/form. At the very least, if going astral doesn't work out you might carry the thought into your sleep, opening the way for some lucid dreams instead.
I agree with Spirit76,
I'll still give you my explanation.
Astral shapeshifting is for me all about believe. You've to believe and convince yourself that the thing you want to achieve in the astral is the only truth acceptable by yourself. Then you'll automatically come to the point where the energy shifts and changes. Your energy will do as you believe. Energy work is controlled by your subconscious. Your subconscious does as your mind believes and will do that also in the astral. For example: (Do not attempt this by any means. I warn you.) Shaolin monks are very skilled in meditation and they work with an energy called Qi. That energy is a kind of life energy that can be used in many cases and for many purposes. That energy can strengthen their body to do things which are naturally not possible. Like keeping their thin arms up while grown up men hang on then. Having a spear but at their throat without cutting it through. Or even have people break baseball bats on their arms, without resting their arm. The scientific force x speed calculation doesn't explain how it is possible in any way if their arms do not rest on some kind of support. Now to come to the point. They can even stop their heart from beating for a few seconds, or until death, by manipulating their subconscious mind with and energy called qi. Therefore, if you do that same thing in the astral, which is easier, you'll be able to manipulate the rules of your being. And the main force behind your subconscious mind is believe.
