SFC you bring up some good points.
As I mentioned, the material is very uniform at first glance and it machines well when all goes well. The impact problem is what did me in.
I know that others have used it to make pen blanks, for example, but the fellow who did this had the Corian supported with a metal sleeve on the inside.
To get around the 'round' issue, I might start with power sanding the square piece with numerous flats (octagon or so) and then carefully turn it to a cylinder.
I am not totally giving up, but for now it is on a back burner.