In accordance with the invention, a MEMs device comprises a component layer, an actuator layer and an intervening spacer. The component layer, the spacer and the actuator layer are assembled at ambient temperature and held together in lateral alignment by resilient spring members. The spacer provides the walls of a cavity between a component and an actuator to permit movement of the component. The walls are advantageously conductive and cover the bulk of the peripheral boundary of the cavity to provide electrostatic isolation and aerodynamic isolation.