Recent manufacturing methods for fabricating flexible devices have attracted a keen interest, with a strong demand by industrial manufactures. For thin film application on flexible devices, slot-die coating was found to be the most suitable method having excellent uniformity. Optimization of the reservoir of slot-die coater should be prioritized, since it is an important parameter affecting the uniformity of the final outcome of the coated layer. However, the numerous designs of reservoir makes prototyping difficult, and also results in high manufacturing cost. This study analyzed the velocity deviation of the slot-die coater outlet using CFD analysis, and shape optimization was performed by contour map. We introduce a facile and low-cost fabrication method for a slot-die coater, using polydimethylsiloxane materials and three-dimensional printing technique. The fabricated polymer slot-die coater was further evaluated by the leakage test of solution.