The present invention relates to a STEM with secondary curvature in extension and to methods of manufacture. In an aspect, an extendible member (10) is provided which is configurable between a coiled form (11) and an extended form (12). The member comprises a longitudinal shell resiliently biased in a slit tube form in which it has a first curvature relative to the hoop of slit tube and has a secondary curvature relative to the longitudinal axis of the member. The slit tube can be opened out at the slit to assume an open form in which it has a flattened cross section in transitioning from the extended form to the coiled form. The strain energy when coiled is lower than the peak strain energy in the member when transitioning from the extended to the coiled form.

Multi-shape products of the present disclosure comprise two components: a matrix component and a fiber component that is embedded or otherwise disposed in the matrix component. The matrix component exhibits certain shape memory properties. The fiber component interpenetrates the matrix component to facilitate fixing of the multi-shape product in various temporary shapes.