Hydrogels are widely used in tissue engineering and scaffold fabrication due to their excellent biocompatibility, while 3D printing excels at creating complex architectures. Among various techniques, low-temperature extrusion-based 3D printing has shown promise for hydrogel scaffold fabrication, as rapid solidification under controlled cooling can improve shape retention during deposition. However, commercial low-temperature DIW systems are often expensive, closed-source, and difficult to customize. Moreover, most require a two-step post-processing workflow involving external freeze-thaw cycles, which can damage structures through mechanical disturbance and temperature gradients, increasing contamination risk. To address these issues, we developed a low-cost, open-source low-temperature 3D printing platform by modifying a commercial FDM printer with custom hardware and upgraded software. It maintains stable − 30 °C ± 1 °C and supports in-situ freezing and freeze-thaw processing. Using a Poly(vinyl alcohol)-lignosulfonate sodium-TEMPO-oxidized cellulose nanofibrils (PVA-LS-TOCNF) hydrogel as the model ink, we achieved stable printing of various patterns and mechanical test specimens, with tensile properties comparable to those from ex-situ freeze-thaw methods. Overall, this platform significantly lowers barriers to low-temperature hydrogel 3D printing and improves accessibility.