LEGO did not invent the plastic building brick.

The original design for the interlocking plastic brick was patented by Hilary Fisher Page, the founder of Kiddicraft, in 1939. These early bricks were called 'Kiddicraft Self-Locking Building Bricks' and featured a similar stud-and-tube mechanism. In 1947, Ole Kirk Christiansen and his son Godtfred visited a demonstration of a Windsor SH4 plastic injection molding machine in Denmark. The machine salesman provided them with samples of the Kiddicraft bricks to show what the machine could produce.The Christiansens recognized the potential of the design but found the Kiddicraft bricks lacked sufficient grip. They spent the next decade experimenting with different materials and internal structures to improve the 'clutch power' or the ability of the bricks to stay together. On January 28, 1958, LEGO filed the patent for the modern brick design that included the hollow tubes on the underside. This specific innovation provided the necessary friction to keep the bricks locked while still being easy for a child to pull apart.Hilary Fisher Page tragically took his own life in 1957, never knowing the massive global success his design concept would achieve under the LEGO brand. Following his death, LEGO continued to dominate the market but faced potential legal challenges regarding the design's origins. To secure their legacy and intellectual property, the LEGO Group officially purchased the remaining rights to the Kiddicraft designs and trademarks from Page's estate in 1981 for approximately 45,000 pounds. This acquisition effectively cleared any remaining disputes over the invention of the iconic toy system.