The enlarged metal strips, scaled up from 1/2" to 40mm, provided two isostatic side frame structures; the side frames are connected by threaded steel rods covered with high density foam upholstered in nappa leather. Wood is used to assure transverse rigidity; the hawthorn was selected for its yellowish colour and traditional use in fine woodworking. Green and red were the basic Meccano colours up to the mid sixties.