Periodic elastomeric cellular solids are subjected to uniaxial compression and novel transformations of the patterned structures are found upon reaching a critical value of applied load. The results of a numerical investigation reveal that the pattern switch is triggered by a reversible elastic instability. Excellent quantitative agreement between numerical and experimental results is found and the transformations are found to be remarkably uniform across the samples. It is proposed that the mechanism will also operate at much smaller scales opening the possibility for imprinting complex patterns at the nanoscale or switching photonic and phononic crystals in a controlled way.