A sub-assembly useful in an electro-optic display includes a conductive layer and a layer of electro-optic medium. The conductive layer has a main section covered by the electro-optic medium, an exposed section free from the electro-optic medium, and a weak section connecting the main section and the exposed section, so that the exposed section can be manipulated to rupture the weak section, thus separating the exposed section from the main section without substantial damage.