biases the tube 106 against the light reflecting surface 73 of the sheet 72 the arm 108 can accommodate variations in tube diameter and assures centering of the tube 106 in the base of the trough each opening 104 and arm 108 are provided by respectively closing and opening corresponding portions of the mold 36 to plastic 88 the underlying supporting body 92 includes an aperture 110 located to expose the back surface 75 of a portion of the sheet 72 adjacent the tube 106 the aperture 110 can be formed by clamping this area of the surface 75 by a holddown pad 70 the aperture 110 provides an area for electrically connecting the sheet 72 to the secondary winding of a flash tube trigger transformer not shown for applying a tube triggering voltage directly to the sheet 72 thus the sheet 72 serves both as a light reflector and as a tube trigger electrode u s pat no 3 484 597 discloses a reflector for an electronic flash unit that also serves as a tube trigger electrode polycarbonate m39 6823 sold by the mobay chemical company of pittsburgh pa under the trademark merlon is a plastic ideally suited to this manufacturing operation this polycarbonate which is heated to about 290 u00b0 c and is pressurized at about 45 kilograms per square centimeter for the molding operation has a high viscosity and thus a low flow rate this is advantageous as it serves to further assure that the plastic is prevented from leaking between the polished surface 73 and the mandrel 56 as the plastic is injected into the mold 36 we have found that the location at which plastic 88 is injected into the mold 36 against the surface 75 is not particularly critical by using.