Which shape is commonly associated with the stretch-out line in sheet metal development?

The stretch-out line in sheet metal development is typically represented as a straight line. This line indicates how the actual length of the flat sheet of metal will be when it is fully unfolded from its formed shape. In sheet metal layout, it is critical to identify the dimensions and configuration of the metal after it has been cut and formed. The stretch-out line helps engineers and fabricators accurately measure and mark how the metal will expand from three-dimensional shapes into a two-dimensional plane.

In this context, a straight line is the most fundamental representation, as it directly correlates with the length of the metal needed before forming occurs. While other shapes like circles, triangles, or rectangles can represent specific features of a design or components within the layout, the stretch-out line itself simplifies the process of visualization, ensuring that the lengths are clear and easily interpretable for cutting purposes.