Leather will conform over time to a given shape it is stretched to. In the case of my belt, the shape is very similar to the unwrapped pattern for an eccentric cone. When forming aluminum or steel plate into shapes, the pattern is precut. Some leather artisans will pre-cut belts this way also. Note the pattern on this shape: the ends are straight where the cone is pretty much a straight cylinder, while the middle has a camber/arc where the shape is flared.
When “rolled,” the front and sides of the belt are straight like a cylinder, but the back flares out for the buttocks. The model confirms that this shape results in an eccentric cone. The developed cut pattern of a concentric cone would have a consistent curve.
While many people prefer the shaped belt like a pair of worn-in shoes, some fastidious fashionistas want their belt hanging STRAIGHT in their closets. If you alternate which way you wear your belt daily, the belt should stretch evenly.