## 3 Results and Discussions  
Figures 7 and 8 present various images of the insole's after testing, with cuts made to highlight potential changes in the gyroid infill structure. The exterior structure of all the insole's remained intact, both during real-life conditions testing and after testing them for flexural strength assessment on the apparatus. Except for the black Fialflex 82A design 1 inside tested under real-life conditions followed by cyclic flexion on the device, none of the insole's exhibited any damage to their internal structures during the flexural fatigue tests. The black Fialflex 82A insole's interior structure failed after around 7000 cycles on the device; delamination between the infill layers occurred, as can be noticed in Figure 7. It is presumed that the damage was a result of wear and tear under specific conditions (such as high temperatures and sweat during the summer) and aging, considering that the insole was subjected to testing a year after being stored in uncontrolled conditions on a shelf. Further investigation is required to validate this hypothesis. Figure 7: Damaged interior structure of black Fialflex 82A TPU (real conditions testing followed by cyclic flexion on the testing apparatus). (**a**) Forefoot area; (**b**) Heel area. Figure 8 presents the evolution of the exterior surface of the varioShore 1 design 1 insole after a specific number of cycles. One can observe the zones with compression marks corresponding to the positions of the two clamps in the forefoot and hindfoot, which compressed the material, leaving non-remanent deformations. In the heel area, the marks vanished quickly between the testing cycles, leaving only surface rubbing marks caused by the clamp area. In the forefoot area, the marks were deeper because the clamping pressure was twice as high as in the heel area, but over time, their intensity also diminished (Figure 9f). In contrast, the compression marks on the Filaflex and PolyFlex TPU insoles were less prominent. This observation was confirmed by the user who tested the insoles for comfort, noting that these deformations, which were perceived as a reduction in rigidity, occurred more rapidly in varioShore insoles compared to the others. The same type of infill failure as for the black Filaflex 82A design 1 was also observed for the blue Filaflex 82A design 2 right foot isosole after 1,423,452 steps. However, the left foot isosole with a 24% infill density in the metatarsophalangeal zone did not fail. In-shoe Pedar measurements (Figure 10) have shown a decrease in the peak pressure when wearing the orthoses. The 3D-printed blue Filaflex 82A design 2 inside reduced the maximum pressures observed in the forefoot area compared to the original inside of the shoes, from 250 kPa to 207 kPa (17% reduction) for the left foot (with 24% infill) and from 305 kPa to 280 kPa (9% reduction) for the right foot (20% infill). These values are smaller than those provided by [PERSON] et al. [23] for flat PORON insoles. The pressure in the heel  
Figure 8: varioShore 1 inside showing no damage of the gyroid infill. Figure 9: varioShore 1 insole top surface evolution: (**a**) immediately after 3D printing; (**b**) after 7000 cycles; (**c**) after 42,000 cycles; (**d**) after 63,000 cycles; (**e**) after 98,000 cycles; (**f**) after 48 h.  
area was redistributed to different hardness zones in the 3D-printed orthosis compared to the central area in the initial shoe insole. For the insoles tested in a real-life scenario, the residual deformation after 1,000,001 steps was around 55% (4.4 mm of 8 mm) for the greater infill and 31.2% (2.5 mm of 8 mm) (Figure 11). The literature on the physical properties of materials used in insoles for diabetic patients is reporting a residual deformation between 10 and 42% after 80,000 testing cycles (this number of 80,000 testing cycles is required in the shoe sole flexing test standards, and it represents just 8% of the real walking test performed for our research) [24]. Figure 11: Measuring the residual deformation of a worn insole.