While sitting in his younger brother Albert's fountain parlor, the Varsity Sweet Shop in San Francisco, Friedman observed his young daughter Judith at the counter, struggling to drink out of a straight straw. He took a paper straight straw, inserted a screw and using dental floss, he wrapped the paper into the screw threads, creating corrugations. After removing the screw, the altered paper straw would bend conveniently over the edge of the glass, allowing small children to better reach their beverages. U.S. patent #2,094,268 was issued for this new invention under the title Drinking Tube, on September 28, 1937. Friedman would later file and be issued two additional U.S. patents and three foreign patents in the 1950s relating to its formation and construction. Friedman attempted to sell his straw patent to several existing straw manufacturers beginning in 1937 without success, so after completing his straw machine, he began to produce the straw himself.

The Flexible Straw Corporation was incorporated on April 24, 1939 in California. However, World War II interrupted Friedman's efforts to construct his straw making machine. During the war, he managed the optometry practice of Arthur Euler, O.D., in Capwells' Department Store in Oakland, California, and continued to sell real estate and insurance to support his growing family. Friedman obtained financial backing for his flexible straw machine from two of his brothers-in-law, Harry Zavin and David Light, as well as from Bert Klein, a family associate. With their financial assistance, and the business advice of his sister Betty, Friedman completed the first drinking straw machine in the late 1940s. Although his original concept had come from the observation of his daughter, the flexible straw was initially marketed to hospitals, with the first sale made in 1947. It is now cited as an early example of Design for All.