Tutmarc's Audiovox Manufacturing Co. was one of the first firms to produce an electric lap steel guitar, and Tutmarc himself was often the demonstrator and promoter. He invented a solid-body electric upright "bull-fiddle" in 1935 but it mainly served as a publicity tool. He manufactured lap steel guitars with his own "blade" pickup, and accompanying amplifiers. His real claim-to-fame was the development and marketing of the fretted and solid-body Audiovox Model 736 Bass Fiddle, from 1936, which was designed to be used in a horizontal position. That then-radical instrument is considered to be history's earliest electric bass guitar—and one that preceded the far more famous Fender Precision Bass by a decade and a half. Tutmarc also manufactured an accompanying bass amplifier, the Audiovox Model 936.