First... you must have a way to control them when you try to roll them. I wound up putting the seeds between newsprint to keep them from flying everywhere.
Second, they crack, but the meats don't separate well enough to either winnow them with air, or float the hulls away from the meats.
That's my experience. Maybe you can get it to work better.
/johnny
I read about that rolling pin method in two places. One of them said put the nuts on a working surface and another said put them in a zip lock bag. The bag would keep them together. Maybe put the seeds in a gallon bag all spread out in there. And, one method was use wind to blow the hulls and another was put them in water.
Tomorrow, I’ll be buying a little wire fence to keep the dog out of the garden and I’ll get Sunflower seeds somewhere and try the rolling pin.
Maybe some 1/4 “ mess screen would hold the seeds in place while you rolled them?