Educational toy made in plastic versions. In the mid-1950s, more explicitly engineering-themed construction toys appeared, including plastic girders, columns, and panels that could be assembled into a model curtain wall skyscraper. Later, this Girder and Panel structural system was extended to a Hydro-Dynamic setup by adding pipes, valves, tanks, nozzles, and pumps to allow construction of model plumbing, HVAC, and chemical engineering systems like a simulated distillation column. Other extensions of the system supported suburban-style housing developments (Build-A-Home), or monorail transportation systems (Skyrail). The building toy Lego was originally developed by Ole Kirk Christiansen in Billund, Denmark, in the 1930s. The name
Lego clone Lego clone A Lego clone is a line or brand of children's construction blocks which is mechanically compatible with Lego brand blocks, but is produced by another manufacturer. The blocks were originally patented by The Lego Group in 1961 as "toy building bricks", and the company has since remained dominant in this market. Some competitors have moved to take advantage of Lego brand recognition by advertising their own products as compatible with Lego, with statements such as "compatible with leading building bricks". The last underlying patents of the brick design expired in 1978, opening the field to rivals. At least