Hard telling. It is certainly possible that balls could have been made of a different material and not gained any real interest. Polyester balls were introduced in 1960, but were not thought of as any great leap compared to the standard hard rubber balls in performance. Only after the introduction of the much harder urethane lane finish around 1970 did the advantage of soft polyester balls, and ultimately urethane and resin enhanced urethane become apparent.
I do remember a couple of guys during the early 60's in our local center bought clear amber balls that were supposedly made out of Lucite. Again while interesting to watch nobody saw any advantage to using them compared to Black Beauties and Three Dots.
