Photoinduced reversible structural changes of anisotropic physical gels are applied to re-writable patterning (see Figure, a photo of a rewritable pattern). The change between a nematic gel and a cholesteric gel via a cholesteric liquid-crystalline sol state is induced by trans-cis photoisomerization of the azobenzene moieties in a chiral hydrogen-bonded gelator blended with a nematic liquid crystal.