Some of the most popular were the 1901 Mills Quartoscope Peep Show, 1904 Mills Electricity is life, 1905 Mills Owl Lifter and the 1920s Mills Bag Puncher just to name a few. In 1926, due to strong growth, the company moved into a huge manufacturing plant of 375,000 square feet comprising a factory and an office administrative building. By May 1935, the company was run by the four sons of Herbert Stephen Mills: Fred L. In the early years of Mills Novelty, they developed incredible gambling machines and equally incredible were their arcade amusement games. The machine was a great success, and the company would later adopt an owl motif as its trademark. The machine's design included a circle of owls perched on a lithographed tin wheel. In 1897, the company launched the Mills Owl, which was the first mechanical upright cabinet slot machine. The company's products also included the Mills Violano Virtuoso, a celebrated machine that automatically played a violin and, after about 1909, a piano.

The Mills Novelty Company of Chicago was a leading manufacturer many coin-operated machines, including slot machines, arcade machines, vending machines and jukeboxes.

Mills novelty company slot machine