👉 In mathematics, undersheathing refers to a type of construction in which an object or structure is constructed by folding it into itself. This process can be used to create various shapes and designs that are not possible with regular construction methods. For example, the shape of a "dodecahedron" (a 12-sided polygon) is constructed using undersheathing. In this case, each vertex of the dodecahedron is folded into itself, creating a single face of the
