## 3 Results
### Feature Importances  
FIs highlight the most important factors for the model's created predictions (adding up to 100%):  
* Laser power \(\times\) scanning speed: 35.9%--proved to be the most influential feature, indicating that this interaction strongly influences the product density;
* Laser power \(\times\) layer thickness: 29.0%--the second most important relationship, pointing to another critical interaction;
* Laser power: 11.8%--moderate standalone impact;
* Scanning speed: 10.7%--moderate individual contribution;
* Scanning speed \(\times\) layer thickness: 9.0%--secondary interaction effect;
* Layer thickness: 3.6%--least influential on its own, but relevant in interactions. In addition, the results for the FIs are visualised in Figure 6 with the help of tree mapping. This visualisation illustrates the relative importances of the individual features used in the model. Each block in the tree map corresponds to a specific feature, and its size is proportional to the influence of the feature on the model's predictions. In other words, the larger the block, the more important the feature is for the outcome of the model. The dominance of the generated interaction terms (together: 73.8%) over the individual features (26.2%) emphasises the usefulness of the selected methods, which leads to a successful capture of the complex relationships in the experimental data. Figure 5: Histogram of standard deviations. **Laser power \(\times\) scanning speed (35.9%)** was found to be the most influential feature. This interaction represents the product of laser power (W) and scanning speed (mm/s) and has an indirect influence on energy density. The results show that higher values tend to increase the relative density of the product, probably due to improved fusion. However, the trend is not linear. For example, at a laser power of 120 W and a scanning speed of 1200 mm/s (product = 144,000), the relative density is 99.263% (improvement compared to [36]), while at 200 W and 2500 mm/s (product = 500,000) it drops to 92.016% (track overlapping, hatch spacing and layer thickness are the same for both). The data show that the relative density increases from 90% to 98% as the product of the chosen parameters increases from 50,000 to 200,000, but decreases beyond 400,000, probably due to over melting. **Laser power \(\times\) layer thickness (29.0%):** A higher power with thinner layers of material ensures more complete melting, which improves density, while thicker layers with insufficient power lead to voids. For example, at a power of 120 W (all other influencing factors at the same value) and a layer thickness of 0.035 mm, the resulting relative density is 99.263%, while at a layer thickness of 0.025 mm, the product has a relative density of 99.975%. The results show a steady increase in relative density with increasing power, with a steeper gradient at thinner layers (e.g., 0.025 mm). However, not enough layer thickness settings are used for definitive conclusions. **Laser power (11.8%):** As an independent characteristic, the laser power contributes directly to the energy density. The analysis shows that increasing the laser power generally increases the relative density of the products, as more energy is available for melting the material. For example, at 65 W, the relative density is 95.952%, while at 55 W, it is 94.959% (the other inputs are left at the same values). However, even if a higher power provides more energy for melting, its effect alone is less significant if the speed or layer thickness is not taken into account. **Scanning speed (10.7%)** has been shown to have the opposite effect on energy density, as it shortens the duration of the interaction of the laser beam with the material particles. Higher scanning speeds generally lead to a lower relative density of the product, as less energy is supplied. For example, at 1100 mm/s (laser power 100 W, layer thickness 0.035 mm, hatch spacing 0.035 mm, ED 51.948 J/mm\({}^{3}\)), the relative density was 94.183%,  
Figure 6: Feature importances presented as a tree map.