Interesting - never heard of anything like that before (at least not in the context of Taiji and cultivation).
Can the ball be taken into the body, or does it stimulate the internal energy structure by being moved over the surface?
It is both within and without -- and I'm not speaking in parables here.
The lower dan tien is always connected to the taiji ball(s). The taiji ball moves energies along the meridians. Depending on the sets/forms we do.
This is about Damo and it's not right to discuss temple style on this thread. My apologies to the OP for distracting the discussion.
If you want to know more let's start another thread to discuss taiji ball work.