Introduction The mechanical properties of trabecular bone are crucial for understanding bone mechanics across different length scales. A tensile testing setup has been previously developed to investigate the mechanical behavior of individual trabeculae [1]. To validate such experimental setups, experiments with standardized samples can be used. Sawbones® material is commonly used as a substitute for bone in biomechanics research. In this study, it is investigated how the mechanical properties of Sawbones® absolute as well as 3D printed samples behave on different length scales. Methods Samples were prepared for two different testing setups: one based on ASTM D638 (Specimen Type V) specifications and another using the custom-made tensile testing setup. The materials used were sheets of Sawbones® material (absolute™ 4th Gen.), a fiber-reinforced composite, and 3D-printed resin (Water-Washable, black, Phrozen). For the custom tensile testing setup, samples with a square cross-section of 0.7 × 0.7 mm were prepared (Fig. 1). Sawbones® samples were CNC-milled (PFK 0203 PX, BZT) in two different fiber orientations: one with the fibers aligned at 0° to the load axis and the other with the fibers aligned at 90° (n = 5 for ASTM D638, n = 3 for individual setup per orientation). Four resin samples per setup were 3D printed (SL1S SPEED, Prusa, CZE) with the same dimensions as milled samples, producing a transversely isotropic material. Due to no fiber reinforcement, it was expected that mechanical properties are similar on the two tested length scales. Tensile tests were conducted under quasistatic, uniaxial tensile conditions on a universal testing machine (zwickiLine Z2.5/TS, ZwickRoell, DE). The main parameter of interest in this study was the ultimate stress of the samples. Results The ultimate stress of resin samples is similar in both testing setups. In the ASTM D638 setup, the mean ultimate stress is 31.36 MPa (± 1.87 MPa), while in the custom tensile setup, it is 29.62 MPa (± 0.91 MPa). For Sawbones®, the results vary with fiber orientation and testing method (Fig. 2). In the ASTM D638 setup, the 0° samples (fibers aligned with the load axis) show an ultimate stress value close to the data sheet’s 106 MPa, though slightly lower. The 90° samples (fibers perpendicular to the load) have a lower ultimate stress compared to the datasheet, which is 93 MPa. For the Sawbones® samples tested in the custom setup, the ultimate stress is lower overall, with the same trend as observed in the ASTM D638 test. Discussion The ultimate stress values for resin samples are similar across both testing setups. This suggests that the custom setup produces valid results. The ultimate stress results for Sawbones® material in normed testing confirm the data sheet values in fiber direction but show lower values for perpendicular testing. This might be due to differences in different batches of the material. Smaller samples result in lower ultimate stresses for Sawbones® material. In the custom setup, the smaller sample size might reduce the influence of fibers due to their lower quantity in smaller specimens. Overall, these findings highlight the importance of not relying solely on datasheet values for composites as Sawbones® material to validate experimental setups, as their mechanical properties may differ significantly due to scale effects. References 1. Bittner-Frank, M., et al, JBMR Plus, 8(6): 2024.