A coupling element (5, 10, 15, 20, 25, 45, 65, 70, 70A, 70B, 70C, 75, 85) configured for single-handed coupling and single-handed de-coupling to another like coupling element to form a chain of multiple coupling elements, each coupling element comprising: an upper body portion; a lower body portion by which another coupling element is able to be suspended therefrom and having a planar flat bottom surface for maintaining the coupling element in an upright position when the bottom surface is in contact with a horizontal underlying surface; and an opening (4, 9) delimited by at least a region of said upper body portion or lower body portion and into which a body portion of another coupling element comprising said upper body portion, lower body portion, and opening, is introducible; wherein each of said coupling elements is rotationally balanced with respect to a corresponding substantially vertically oriented center line to ensure that the bottom surface, when said coupling element is suspended and lowered, will remain substantially horizontal even if it was initially at an acute angle with respect to the underlying surface, due to a subsequent rotation of said suspended coupling element about its center of mass, thereby facilitating one-handed intercoupling of a suspended coupling element or a chain of successively suspended coupling elements to another coupling element that is initially disposed upright on said surface and to allow one-handed decoupling of a lowermost coupling element in said chain while maintaining the lowermost coupling element upright on said surface; characterized in that: the upper body portion and lower body portion form a peripheral body (2, 31) that defines said opening (4, 9), and the opening (4, 9) includes a slot (3, 8, 43) into which the peripheral body of another like coupling element is introducible whereby the two coupling elements are loosely intercoupled and are decoupled by lowering the chain of multiple coupling elements so that the lowermost coupling element stands upright on said surface and removing the peripheral body (2, 31) of one coupling element through the slot (3, 8, 43) of the other coupling element. an upper body portion; a lower body portion by which another coupling element is able to be suspended therefrom and having a planar flat bottom surface for maintaining the coupling element in an upright position when the bottom surface is in contact with a horizontal underlying surface; and an opening (4, 9) delimited by at least a region of said upper body portion or lower body portion and into which a body portion of another coupling element comprising said upper body portion, lower body portion, and opening, is introducible; wherein each of said coupling elements is rotationally balanced with respect to a corresponding substantially vertically oriented center line to ensure that the bottom surface, when said coupling element is suspended and lowered, will remain substantially horizontal even if it was initially at an acute angle with respect to the underlying surface, due to a subsequent rotation of said suspended coupling element about its center of mass, thereby facilitating one-handed intercoupling of a suspended coupling element or a chain of successively suspended coupling elements to another coupling element that is initially disposed upright on said surface and to allow one-handed decoupling of a lowermost coupling element in said chain while maintaining the lowermost coupling element upright on said surface; the upper body portion and lower body portion form a peripheral body (2, 31) that defines said opening (4, 9), and the opening (4, 9) includes a slot (3, 8, 43) into which the peripheral body of another like coupling element is introducible whereby the two coupling elements are loosely intercoupled and are decoupled by lowering the chain of multiple coupling elements so that the lowermost coupling element stands upright on said surface and removing the peripheral body (2, 31) of one coupling element through the slot (3, 8, 43) of the other coupling element.