Patient-tailored, 3D-printed surgical guides offer significant potential to improve precision and therapeutic efficacy in cardiac ablation surgery. However, reliable post-sterilization material performance presents a critical yet underexplored barrier to clinical adoption. This study investigates how disinfection and sterilization impact the mechanical and thermal properties of photopolymer resins. Specimens from two 3D-printing resins (Bioflex A80 MB{\texttrademark}, 3Dresyns; MED625FLX{\texttrademark}, Stratasys) were treated with four combinations of disinfection techniques (low-temperature manual cleaning; high-temperature machine washing) and sterilization techniques (H2O2 vs. autoclaving). We assessed post-sterilization properties by mechanical (material integrity, bending tests), thermal (differential scanning calorimetry, thermogravimetric analysis), and viscoelastic (dynamic mechanical analysis) studies. Statistical analysis was performed using one-way ANOVA with Bonferroni post hoc tests (α = 0.05). From this preliminary study, we conclude that MED625FLX maintains integrity and flexibility across all tested disinfection and sterilization methods. Bioflex A80 MB is only suitable for low-temperature disinfection–sterilization, as high-temperature treatments cause surface cracking. Neither resin is appropriate for cryogenic conditions due to the risk of brittleness. Further research into post-sterilization properties is essential to ensure the safety and clinical reliability of these materials in cardiac procedures