## 4 Results and Discussion
### Discussion and Integrated Assessment  
Table 6 synthesizes the key findings. SLA excels in surface finish, dimensional accuracy, and tensile strength, while FDM is superior in cost, throughput, and environmental impact. A multi-criteria analysis (Figure 5) highlights the trade-offs, with SLA marginally leading overall but FDM being preferable for cost-sensitive applications. Comparison with Prior Studies  
Several studies have explored the comparative performance of FDM and SLA across various parameters, including surface finish, dimensional accuracy, mechanical properties, and cost-effectiveness. Our results are in general agreement with previous research but also introduce novel insights into material behavior under standardized conditions. \begin{table}
\begin{tabular}{l c c c} \hline \hline
**Metric** & **FDM (PLA)** & **FDM (ABS)** & **SLA (Resin)** \\ \hline Surface Roughness (\(R_{a,}\)\(\mu\)m) & \(12.1\pm 1.2\) & \(13.5\pm 1.4\) & \(2.2\pm 0.3\) \\ Dimensional Dev. (mm) & \(\pm 0.15\)–\(0.20\) & \(\pm 0.15\)–\(0.20\) & \(\pm 0.05\) \\ UTS (MPa) & \(50.2\pm 2.7\) & \(47.5\pm 3.1\) & \(68.9\pm 3.0\) \\ Elongation at Break (\%) & \(5.8\pm 0.6\) & \(8.7\pm 0.8\) & \(4.4\pm 0.3\) \\ Cost per Part (EUR) & \(2.30\) & \(2.50\) & \(5.90\) \\ Build Time (min) & \(45\)–\(50\) & \(50\)–\(55\) & \(90\)–\(100\) \\ Energy Use (kWh/part) & \(0.75\)–\(0.80\) & \(0.80\)–\(0.85\) & \(1.0\)–\(1.1\) \\ Waste (\% by mass) & \(15\)\% & \(15\)\% & \(10\)\% \\ Waste Type & Biodegradable/Recycl. Recyclable & Hazardous resin \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Summary of main comparative findings for FDM vs. SLA. Figure 5: Illustrative multi-criteria radar chart (each criterion weighted 20%). Aggregating the weighted scores yields final averages: FDM (PLA) = 7.1, FDM (ABS) = 6.8, SLA (Resin) = 7.4. For surface roughness, our findings align with [PERSON] et al. (2022) [12], who reported that SLA achieves a significantly lower \(R_{a}\) compared to FDM. Similarly, [PERSON] et al. (2010) [5] emphasize the superior surface finish of SLA due to its laser-based curing mechanism. However, while previous studies primarily focus on as-printed surfaces, our research extends the analysis by quantifying the impact of post-processing (e.g., polishing, acetone vapor smoothing), demonstrating that FDM roughness can be reduced by nearly 50%, though SLA remains inherently smoother. In terms of dimensional accuracy, our results (SLA: \(\pm\)0.05 mm; FDM: \(\pm\)0.15-0.20 mm) are consistent with [PERSON] et al. (2008) [9] and [PERSON] et al. (2022) [11], who found that SLA tolerances are typically within \(\pm\)0.05 mm due to its high-resolution laser curing process. However, we also identify that FDM exhibits greater anisotropic deviations, particularly along the \(Z\)-axis due to layer-by-layer deposition. Regarding mechanical properties, our findings confirm the anisotropic nature of FDM reported by [PERSON] et al. (2002) [4], where interlayer bonding significantly influences tensile strength. [PERSON] et al. (2014) [15] similarly noted that ABS filaments achieve higher ductility compared to PLA, which is reflected in our results (\(\epsilon_{b}=8.7\%\) for ABS vs. 5.8% for PLA). However, our work extends this by incorporating SLA stress-strain analysis, confirming its brittle failure mode, which is less discussed in prior work. In terms of cost-effectiveness, our results are in line with [PERSON] et al. (2015) [18], who found that FDM is at least 50% cheaper per part than SLA due to lower material and equipment costs. However, our study additionally evaluates energy consumption and waste management, showing that while SLA prints are costlier, they also generate slightly less waste by weight but require specialized disposal procedures. Environmental considerations are often overlooked in prior studies. [PERSON] et al. (2020) [19] and [PERSON] et al.