I have been asked about the "OATS" stave segmented turning blanks:
This is an image I constructed in PhotoShop. Basically, this kind of blank is made with 8 45/45/90 triangles, long enough to turn the form I want. The center will always be open, and that is what creates the illusion of motion/curved segments.
So long as the angles are correct, the triangles can even be of different sizes. That actually creates an additional interesting result.