a foldable structure which can be used as the basis for a wide variety of articles , such as furniture , office equipment , freight containers and portable buildings , is foldable between a generally flat form and an erected , three - dimensional form . a first pair of opposed frame units are connected by at least one further frame unit , which is hingedly attached to one of the pair of frame units and is hingedly and slidably attached to the other of the pair of frame units , for example by means of swivel cleats . further components are connected to one or both of the pair of frame units so that such further components can be disposed in a folded - flat position adjacent to said pair of frame units when the latter are in their collapsed state and can be disposed in a second , ready - for - use position in planes at an angle to the planes containing the frame units to which they are attached .