Anything is possible, but there are some limitations of physical reality that you are by your choice on the spiritual level more likely to transcend than others.

The reason it is not likely that you can get instant manifestation of everything all the time through belly breathing is because the whole point of having physical reality is to experience its limitations. The excitement you feel about manifesting in the challenging-to-influence dimension comes from the very fact that it is the challenging-to-influence dimension- physical reality is like a limited edition product. It's exciting because it's limited.

Your imagination is just as real as physical reality, and you already have instant manifestation there. Red ball in the air? Poof, there you have it. Manifested instantly. The physical dimension is no different from imagination, it's all reality- The point is that you think the physical dimension is more exciting. But that is because it is limited. If you could manifest instantly in the physical dimension, it would no longer be the physical dimension, and it wouldn't be any more interesting to you than your imagination is now.

Having said that, by all means use belly breathing to manifest faster. I like the Huna concept of Haipule for manifesting; you energize by breathing, you affirm with words, you imagine, you act, and you let go, all in one fluent technique. So energy breathing is certainly a great idea, and you should do it, since it would appear that it interests you. However, it's purpose is to energize a dream you are creating in your imagination, which will eventually turn up in the physical dimension when you've energized it enough. The purpose is not to completely unlock the way physical reality works. After all, you chose it, and for good reason.

I like the honesty of the idea I also got from Huna that spiritual techniues are more like digging a hole with a shovel than like waving a magic wand once. You keep going until the job is done.

Having said all of that, this is my experience based on my spiritual choices- I have heard stories of people insta-manifesting small objects or even whole organs for transplant out of thin air, but I haven't been able to find specific people who can do this who can explain it in a way that is credible to me. In my experience, things that are dimensionally impractical usually manifest as near equivalents. So, for example, if I wanted to insta-manifest a certain person, I would start taking my imagination more seriously so I would have the experience of having insta-manifested, without going through all the energy trouble of actually doing it. And lo and behold, turns out the experience was all I really wanted. So I suspect actual insta-manifestation comes when the time is right, and that is when you, spiritually, are done with messing around in physical reality as it is now. Personally, I love physical reality. Its puzzlingness tickles me in ways that little else can, which is why I believe that I have chosen to specialize on earth. I want to surf the waves, not boil the ocean into steam.