There is a 3 side triangle where the pointed corners are made
round. I am not sure what this shape is called. The diameter
through the middle is the same all the way around the
triangle. Sounds to me like according to one defination that the
diameter of a sphere is equal all the way around then this 3 sided
thing is a sphere too. To bad I can not draw a pic and post it
here. There use to be some pics on the MIT web page.
Gary"
Another interesting property of this shape when it is extended
into a cylinder is that it produces a roller which behaves exactly
like a round one.
Ed