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In this study, 3% w/v kappa-carrageenan (кC) and 2% w/v agar were assessed for their suitability for hot extrusion 3D printing (3DP) and compared to cast gels of equivalent composition. Moreover, incorporation of a model active (thiamine) at varying concentrations, was studied for both 3DP and cast microstructures. Rheology and differential scanning calorimetry showed that thiamine (via electrostatic complexation) reinforced the kappa-carrageenan gel network (up to a certain threshold concentration), whereas the agar gel was structurally unaltered by the active's presence. While the кC-thiamine formulations were printable (within a relatively narrow formulation/processing window), the agar-thiamine systems were not printable via the current set up. Texture profile analysis (TPA) showed that 3DP кC-thiamine cylinders had a hardness value of 860 g ± 11% compared to 1650 g ± 6% for cast cylinders. When …