spacing them closer increases the risk of fiber to fiber contact near the terminal end portions when the ends are potted preferred center to center spacing is from about 1 5d to 2d the thickness of a strip and or adhesive is sufficient to ensure that the fibers are kept spaced apart preferably the thickness is about the same as or relatively smaller than the outside diameter of a fiber preferably from about 0 5d to 1d thick which becomes the spacing between adjacent outside surfaces of fibers in successive linear arrays having formed a first array a second array not shown because it would appear essentially identical to the first is prepared in a manner analogous to the first strip 15 of the second array is overlaid upon the intermediate portions 12 u2032 on strip 15 of the first array the strip 15 of the second array resting on the upper surfaces of the fibers secured in strip 15 of the first array similarly strip 16 of the second array is overlaid upon the intermediate portions 12 u2032 on strip 16 of the first array a third array essentially identical to the first and second is prepared in a manner analogous to the first and then overlaid upon the second with the strips of the third array resting on the upper surfaces of the fibers of the second array additional arrays are overlaid until the desired number of arrays are stacked in rows forming a stack of arrays with the adhesive coated strips forming.