I. Introduction
The use of Additive Manufacturing (AM) technologies is becoming more and more diffused in different application fields, thus changing the traditional production paradigm. AM can lead to different benefits, from the reduction of the environmental impact if compared to traditional manufacturing [1], to the possibility of obtaining advantages in the realization of more effective products, specifically designed for AM realization [2]. This is true even for the framework of electromagnetic applications in which the exploration of the third dimension could be a key-factor to offer advantages in terms of performance, conformability, or effectiveness of different electromagnetic devices like antennas, microwave filters and circuits [3 –12].