Williams Brothers began their operation in 1960 in a small garage in Hunnington Park, California, while Granger and Larry Williams were both still working in the wind tunnel section at North American Aviation. Their first molds were for nylon bellcranks and hinges. This, because Granger recalls, was that he needed those items for his own airplanes, and he felt that other fliers would need them.

By 1963 the small time operation had grown out of their garage and into a 1000 square foot industrial building in Bell, California. As production fell behind orders, they found themselves looking at injection molding equipment. At the time the new machines didn't fit their idea of what they should be like, so Granger and Larry built their first machine. Although the machine has since been retired and replaced with new ones, it still could do things that new ones can't.

In 1970, Granger and Larry packed up and headed for San Marcos, California. There they built a modern day industrial building that would carry their company into the 21st century. By this time the company was producing much more than the nylon hinges and bellcranks. They had gone into plastic spinners, wheels, pilots, engines, engine cylinders, machine guns, wheel pants, pylon racer kits and plastic scale model kits.

In 2000, both of the Williams Brothers passed on and Granger's wife Lorraine took over the company which ran until the end of 2004.

In 2005, the assets of the company were purchased by Daniel J Brett, who incorporated in the State of Texas under Brett Industries, Inc. and the operations moved to Taylor, Texas where production was continued.

At present Williams Brothers Inc. will once again produce the 21 plastic plane kits, 23 HO Scale car kits, 14 engine cylinders, 7 complete engine kits, 4 different style pilots in 5 or more sizes and 4 different style wheels in up to 10 different sizes. All this and still more to come.