Abstract: Elastic thread lines can extend along borders of puckering areas of a fabric. The thread lines can include elastic thread line sections of the thread lines passing through thread line intersections and segments of the thread lines between the intersections. The elastic thread lines can bias the puckering areas in multiple different non-parallel directions toward a puckered configuration. In the puckered configuration, the puckering areas can be gathered together to pucker the fabric. The fabric can be stitched together to form a product, such as a sleeping bag sack that is stretchable in multiple orthogonal directions by stretching the thread lines. Elastic thread line sections passing through intersections can be made more secure by forming thread line section patterns that increase numbers of thread line crossings at the intersections. Densities of thread lines in different directions can be selected to produce different amounts of gathering, and for security.