An innovative approach to the synthesis of wave manipulating devices is proposed in this work within the framework of the System-by-Design (SbD) paradigm. The approach is based on the decomposition of the overall synthesis problem in terms of the combination of a set of functional blocks, each one performing a 'simple' task. The design blocks (each one aimed at the analysis or synthesis of a specific sub-part of the wave manipulating device of interest) are then combined in a SbD loop to yield the final design procedure. Representative numerical examples are reported concerning the design of different wave manipulating devices to assess the features and potentialities of the proposed SbD approach