About a year ago, on eBay in some country in Europe, don't recall where, there is a company that sells different versions of these.
Just the splitting cones, not the motor, as far as I recall, in several different sizes, a couple that could be used on handheld drill motors, and seemed to work extraordinarily well.
I would most likely have purchased one, but they were more then I could afford at the time.
I remember thinking that if they really do work this well, sooner or later someone here in the U.S. will start making them, or importing them and maybe then I could get one.
Also thought about showing some of the videos, (there were several videos the company made) to a machinist friend, and seeing what he thinks.
RicklesssS in Oregon