Fatigue is one of the most significant causes of spring damage. Since fatigue tests play a crucial role in predicting the lifespan of springs, many special test device and test techniques have been described in the literature. In this paper, the significant design and manufacturing steps of a newly developed eccentric spring fatigue testing device are introduced. This device is particularly suitable to perform fatigue life tests on high rigidity springs, such as mold springs. This low-cost device can be used on springs at many different load ratings. In this study, the fatigue process of metal springs and a case study regarding the development and manufacturing process of a new fatigue testing device are described. Furthermore, the fatigue test procedure on metal springs and some test results generated by the spring fatigue test device are also presented.