This book presents fused deposition modeling (FDM) which is an additive manufacturing (AM) process to fabricate 3D parts from a build-up of 2D layers. The chapters present an experimental analysis of fatigue characteristics of FDM-processed PLA samples. The results indicate that the concentric build orientation provides highest cycles of fatigue, ultimate strength, and impact energy. The effect of layer orientation on the fatigue behavior of 3D-printed PLA samples is investigated in this case study.