## 3 Discussion of the Results
### Analysis Limitations and Further Research  
The analyzed case represents a simplified example with arbitrarily set loading conditions, as the theoretical 300 J of energy served as an artificial benchmark for comparison purposes. Real-world impacts would likely lead to stiffer responses from the tested prototypes. The assumed deformation energy ensured a comparison of the mechanical resistance values of the tested prototypes, as shown in Figures 9b, 10 and 12. These test specimens demonstrated distinct deformation resistance values and cannot be compared without introducing a more or less realistic deformation limit. At the same time, the mechanical test results (Figures 9 and 10) do not reflect the loads of real collision scenarios. Therefore, future studies must use drop-weight or dynamic tests for UAV design purposes. However, these tests are not essential for the current comparative framework, which emphasizes illustrating the efficient deformation energy absorption by LW-PLA metastructures. The core message of this analysis pertains to the comparison conditions, and the deformation energy can function as a reliable measure to evaluate the efficiency of the FFF structures. In this scenario, the front collision at the drone's cruise speed determines the analysis benchmark. The support conditions of the fuselage prototypes are also hypothetically simplified. Real-world situations may involve various constraints that will affect the design output; however, the generalized design steps presented in this manuscript will remain unchanged.  
This study incorporates heuristic optimization procedures to focus the analysis on the design steps and characterization processes of the materials. However, further research should incorporate advanced optimization algorithms, as considered in reference [43], to ensure a multi-objective solution that accounts for realistic constraints.  
While this study successfully demonstrates the feasibility of using LW-PLA in drone fuselage components, several additional limitations merit attention. First, the study does not examine the fatigue behavior of the materials under cyclic loading, which is critical for drones subjected to repeated takeoffs, landings, and in-flight vibrations [2]. Second, the interaction between the printed parts and other drone components (e.g., electronics, fasteners, and adhesives) was not considered, which may impact integration and long-term reliability. Third, the scalability of the proposed DfAM approach to larger drones or more complex geometries remains untested.  
Environmental conditions also influence the performance of polymeric materials [42; 46; 47], which compromises their mechanical resistance and energy absorption capabilities. In drone applications, temperature and humidity conditions establish key constraints on the mechanical resistance and durability of polymeric materials [2; 47]. However, extending the DfAM design methodology may necessitate additional mechanical characterization means and conditions.  
Future research should also explore the anisotropic behavior of LW-PLA under multi-axial stress states, as well as the impact of print orientation on crashworthiness. Moreover, integrating sensor-embedded structures, such as those in [33; 47], could create new opportunities for real-time structural health monitoring in drones.