This research examines the fatigue performance of 3D-printed coil springs used in robotic finger mechanisms, comparing PLA and ABS materials. Springs were manufactured with two distinct geometric configurations and tested under cyclic loading on an in-house developed fatigue test bench. The study investigates the effects of material properties, printing parameters, and spring dimensions on fatigue life. Results show that ABS demonstrates superior fatigue resistance, sustaining significantly more cycles before failure compared to PLA. ABS springs endured up to 24,670 cycles, while PLA springs failed after 7652 cycles in comparable conditions. Key findings highlight ABS's enhanced durability under dynamic stresses, attributed to better ductility and energy absorption, making it ideal for high-stress, long-term applications. In contrast, PLA's biodegradability and lower fatigue resistance suggest its suitability for low-stress, short-term, or environmentally conscious applications. The study also underscores the critical role of geometry and preloading in determining fatigue performance.