Some experiments for studying the effects of explosively induced shock waves require that the detonation front lie in a straight line in a thin sheet of explosive. Since explosives are conventionally point initiated, a device must be used to convert the curved detonation front into a straight front. This conversion has been achieved in a practical fashion by point initiating a thin sheet, properly shaped, of easily molded explosive. Some satisfactory shapes which can be produced by standard shop methods are described.