I have some experience with psi balls.
Here is where knowledge of 'implosion/concentration' and 'emanation' comes in handy.
If you want to make a proper psi ball, first, make the basic type. There are two basic types that I know.
1. DIRECT- here, you concentrate your own psychic energy to form the psi ball, your mind is automatically linked to the psi ball and you will actively control it with, as Ryan said, your intentions, also, your beliefs, thoughts, and visualizations
2. EMANANT- here, you form an external chakra by drawing and containing raw psi from the infinite vaccum, it is pure potential
Those are just terms that I am giving to try to explain it.
Perhaps they can be used?
Well, once you have your basic psi ball, you can expand it. Expanding it is different than emanation. When you expand it, the core of the psi ball should still be emanating itself, to fuel the dimensional increase.
Remember, there are many different techniques for handling psi balls. However, these techniques are very specific, color codes, emotional infusions, sexual energies, and all things like that. Even your celestial map plays an important role in the eventual psi ball that you generate. Yes! You can manifest physical objects.
One time, I was laying in bed after an experience with Jesus Christ, God Bless His Name, and I had increased telekinesis. So I decided to try and make a psi ball. In my psychotic energy state, I rubbed my hands together, performed the psi test, then, I visualized intense red and black energy into the space of the psi ball, and, began to crystalize it with will power. When I was finished, I crushed the poor thing, and there was a pulse of power. After that, I looked at my hands, and behold, there was small flakes of pure white gold all over my hands.
Psi Balls are not an easy magick, it takes much time, powering up and keeping your chakra system healthy, and experimentation to find what works for you. As a side note, I tried that red and black crystal rock technique again one time, and the same thing happened. But in your case, the red and black might form little shards of organic matter, or some kind of parasite, or even something radioactive.
It would be good if you mastered levitation before you attempt psi balls. I won't say why, but I can add to it, if you can levitate, then you have a stronger, more animate body.