In the past three decades number of studies have been reported on electrochemical machining (ECM) of conducting materials based upon the electrochemical equivalent of tool and work material. But hitherto little has been reported on the use of thermoplastic composite slit as a guide for the flow of electrolytes and tool movement to enhance the performance of the ECM process (in form of dimensional stability, surface porosity, surface roughness, etc.). In this work, 3D printed PA6-50%Al composite matrix slit has been used formachining of Al alloy substrate with Cu alloy as a tool with ECM process. For comparing the performance of ECM on Al substrate two pre-drilled holes (of different diameters) were made as a slit in PA6-50%Al. The results of the study show that in the case of slit diameter less than tool diameter the aspect ratio obtained is better than the case with slit diameter equal to the size of the tool. Further comparison has been made without the use of slit while machining Al alloy for establishing the performance of ECM. The results have been supported by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and dimensional measurement in this case study.