Abstract
Replacement of each 4-ring in a stack of congruent 2D nets by a double-bifurcated chain leads to new 3D nets. Each 3D net is turned into 3 more nets by applying a σ-transformation either in the plane of each original 2D net, or through each bifurcated chain, or both. The simpler nets with highest symmetry are enumerated for the 4.82 and 4.6.12 2D nets. A further type of net is obtained by transforming each σ, σ-double-bifurcated chain from the rod symmetry group pmmm to p42/mmc by a screw operation.