The combined use of computer-aided design & engineering resources and of additive manufacturing technologies for solid freeform fabrication, allows for the precise control of material properties and enables the development of devices with complex geometries. The possibility of defining both material features and device geometry, even from the design stage and with a relevant degree of precision and complexity, promotes the incorporation of advanced functionalities and the integration of functions. The employment of an adequate design methodology, aimed at taking into account the potentials of solid freeform fabrication, can prove to be very adequate for the straigthforward development of solutions for improved heat transport and heat dissipation and for obtaining materials and devices with predefined structural and thermal performances linked to complex specifications. In this study we present the interest of using materials and devices with complex geometries (i.e. porous structures, lattice networks, functionally graded structures) for controlling mechanical and thermal properties within complex devices and the related development methodology. Such methodology is illustrated by means of real applications linked to heat exchangers and heat dissipators with direct application in energy engineering.