Nevertheless, this angle acts as a dihedral which, together with the vent between the cells, gives good stability. Here are plans for a traditional box kite using a kitchen garbage bag and some dowelling. Improved lift can be had for an insignificant loss of stability by flattening it a little, resulting in the rhomboid kite . Plans for a rhomboid are given by Eden . Eden also gives plans for a winged box.
Plans are also available.
A particularly striking variant is the Pely Box, also known as the Tri-D , which is made entirely out of identical isoscoles triangles. It gets its name from its inventor, Pe ter Ly nn. As compared with the traditional box, this design saves the weight of two of the four longerons at the cost of some sail area. This sketch shows a 3-cell version because, after several abortive attempts to draw it, I got carried away. But when I built a 3-cell pely, it turned out disappointingly unstable.