In this paper, a novel fully inkjet-printed via fabrication technology and various inkjet-printed substrate integrated waveguide (SIW) structures on thick polymer substrates are presented. The electrical properties of PMMA are thoroughly studied up to 8 GHz utilizing the T-resonator method, and inkjet-printable silver nanoparticle ink on PMMA are characterized. A " long via " fabrication process up to 1 mm utilizing inkjet printing technology is demonstrated and its characteristics are presented for the first time. The inkjet-printed vias on 0.8 mm thick substrate have a resistance of about 0.2 Ω. An equivalent circuit model of the inkjet-printed stepped vias is also discussed. An inkjet-printed microstrip-to-SIW interconnect and a SIW cavity resonator utilizing the proposed inkjet-printed via fabrication process are also presented. The design of the components and the fabrication steps are discussed, and the measured performances over the microwave frequency range of the prototypes are presented. Index Terms—Additive fabrication, inkjet-printed Substrate Integrated Waveguide (SIW), inkjet-printed via, low-cost via fabrication, Polymethyl methacrylate (PMMA).