Elastically deformable materials can be created from rigids sheets through patterning appropriate meshes which can locally bend and flex. We demonstrate how micro-accordion patterns can be fabricated across large areas using three-beam interference lithography. Our resulting mesh induces a large and robust elasticity within any rigid material film. Gold coating the micro-accordion produces stretchable conducting films. Conductivity changes are negligible when the sample is stretched reversibly up to 30% and no major defects are introduced, in comparison to continuous sheets which quickly tear. Scaling analysis shows that our method is suited to further miniaturisation and large- scale fabrication of stretchable functional films. It thus opens routes to stretchable interconnects in electronic, photonic and sensing applications, as well as a wide variety of other deformable structures.