Abstract: A method of constructing vehicle frames of varying lengths from a flexible modular architecture is provided. The method comprises: providing substantially identical front and rear modules, and providing middle modules with constant-section longitudinal rails that are formable to a variety of desired lengths. The components are selected by trimming or forming a first middle module to a first longitudinal length and selecting one each of the substantially identical front and rear modules. A first frame, having a first frame length, is then assembled from the formed first middle module and substantially identical front and rear modules. After forming another middle module to a second length; a second frame, having a different frame length, may then be assembled from the second formed middle module and a second pair of substantially identical front and rear modules. An assembly for constructing frames of varying lengths from a flexible modular architecture is also provided.