A process produces self-illuminating bodies, in which a recess is made in a housing part of a housing and a fluorescent and/or phosphorescent layer and/or a mask is arranged on a boundary wall of a cavity which is formed by joining the housing parts together. The housing parts are connected in a gastight manner, with at least one feed opening from outside into the cavity remaining open. Furthermore, a medium emitting decaying radiation is introduced through the at least one feed opening into the cavity, the decaying radiation being intended to illuminate the fluorescent and/or phosphorescent layer. Furthermore, a self-illuminating body and also the use thereof are specified.