To highlight the advantages of 3D printing for iontronics, we apply the above characterized conductive ink along with other extrusion-based inks to rapidly fabricate and iterate iontronic components and devices. First, we use multi-material printing to fabricate ionic diodes of different geometries. In addition to the PEDOT:PSS conductive hydrogel, we optimized inks for printing a cation exchange hydrogel, which selectively allows the diffusion of cations while limiting the diffusion of anions, and an anion exchange hydrogel, which selectively allows the diffusion of anions while limiting the diffusion of cations. Several research groups have demonstrated ionic diodes utilizing similar charge selective materials in the shape of two trapezoids or triangles. With this design, it can be expected that the ion selective hydrogels will pull apart as the device is stretched, and Lee et al. demonstrated that their ionic diode was sensitive to strain as stretching resulted in decreasing conductivity. It might be desired in some applications that a certain amount of stress causes the circuit to open, resulting in a mechano-responsive circuit. However, other situations might require a diode that retains its functionality without being impacted by stretching, in which case a different geometry must be implemented. In Figure , we 3D print the traditional strainsensitive geometry as well as a new geometry where the cation and anion selective material are 3D printed in shapes that hook around each other. As this diode is stretches, the materials cannot pull apart. The IV plot supports that, unlike the previously established geometry, the hooked diode is largely unaffected by the strain. We also incorporated a PDMS ink that could be UV crosslinked, thereby using the same polymerization method for all inks presented in this work, to encapsulate the ionic diodes. It can be noted that the new hooked geometry results in much higher resistance and could likely be further improved. By using extrusion printing, we were able to print one design immediately after the other, and similar rapid iteration could be used to explore additional diode geometries. In comparison, previous work relied on laser cutting, microfluidics, and several assembly steps, which is much more labor intensive than what can be offered with extrusion printing. We also utilize the versatility of 3D printing to print on different substrates, creating diodes within the PDMS as well as on extremely flexible VHB tape as used by previous work. Beyond the advantages of the fabrication method, the characterized PEDOT:PSS hydrogel also provides advantages compared to previous work. While previous work used atomic salt solutions as an ionic reservoir, the voltage rectification shown in Figure supports that the PEDOT:PSS laden hydrogel is a suitable replacement. Whereas atomic salts might diffuse out of a hydrogel when wet, PEDOT:PSS remains within the double network of the hydrogel. We found that this diode can be submerged in deionized water and its functionality remains the same for at least 3 hours. Although the diode is encased in PDMS, the ends of the PEDOT:PSS hydrogel are left exposed to the deionized water. Hydrogels that utilize unbound charge carriers would not maintain a consistent behavior in the same environment. iii) The resistance is evaluated using an IV plot as the printed structure experiences different amounts of strain. This provides a control experiment to demonstrate how the material resistance changes with strain. D) i) A 3D model of an ionic diode using the traditional established geometry. ii) A photo of the traditional diode extrusion printed from the model. iii)