Electrical discharge die-sinking machining (EDM) is one of the indispensable unconventional technologies enabling the machining of all materials that are at least minimally electrically conductive. Due to the clear trend of miniaturization of products, it is necessary to ensure their quality and accurate production, also with the help of micro-EDM. It is the optical instruments used for testing car lights that contain these miniaturized parts necessary for the correct functioning of the device. For this reason, this study was performed, which focused on the production of a precise slot measuring 5000x170 µm in a copper foil with a thickness of 125 µm. The same copper foil was used as a tool, which represents an advance in the production of micro-parts. A design of experiment Box and Behnken Response Surface Design was performed for a total of 15 rounds, monitoring the effect of machine setting parameters (Pulse current, Pulse on time and Voltage) on responses in the form of Erosion rate, corner radius, slot length and width. Using multi-criteria optimization, the optimal setting of the machine parameters for the production of a given slit was determined, which is Pulse current = 2.1 A, Pulse on time = 40 µs and Voltage = 238.8 V.