A cylindrical metal end cap is formed over one end of a thermoplastic tubular casing. A pyrotechnic detonator is ohmically connected to the end cap via an aperture thereof and includes an electrically activated match. The detonator is soldered to the end cap with a solder ring simultaneously with the insertion of the detonator into the end cap aperture to form a hermetic seal. A thermoplastic end cap is heat welded to the other end of the casing to hermetically seal the pyrotechnic material within the casing. The heat welding occurs at the outer surface of the casing and at a temperature lower than the ignition temperature of the pyrotechnic material in the casing. The position of the match within the casing is selected to cause the pyrotechnic material to burn toward the metal end cap to enhance flash production, different length casings producing different flash intensities.