Metal-coated polymer electrodes fabricated by additive manufacturing are promising tools for electrical discharge machining (EDM) of complex shapes; however, coating non-uniformity and thermomechanical degradation limit their performance. This study presents experimental and theoretical results for a hybrid tool electrode fabricated by stereolithography (SLA), followed by electroless and electrochemical copper plating, and used to machine St3 structural steel. Optical and scanning electron microscopy, energy-dispersive spectroscopy (EDS), atomic force microscopy, X-ray microtomography, Raman spectroscopy, simultaneous thermal analysis and nanoindentation were used to characterize the coating before and after EDM. The electroplated copper layer exhibited pronounced thickness non-uniformity (264–1225 µm), an edge effect and dendritic morphology associated with the primary current distribution and the absence of leveling additives. Surface modification during EDM was accompanied by changes in the elemental composition measured by EDS. After EDM, the Fe and C signals reached 23.32 wt.% and 35.56 wt.%, respectively, under the acquisition and quantification conditions used. These values characterize local surface composition and do not establish bulk incorporation of iron or carbon into the copper layer. No pronounced bulk thermal degradation was detected in the examined photopolymer specimens; exposure of the polymer base nevertheless promotes local damage. A coupled numerical model combines a boundary element calculation of copper deposition, normal coating recession and cavity formation; a single-discharge thermal solver provides diagnostic calculations. The model describes the principal copper-wear and cavity development trends for the investigated electrode, including the end face and chamfer and reproduction of coating and printing defects. Because only one electrode was fabricated, plated and tested, the work is presented as a detailed case study. The observed variability reflects within-specimen measurement scatter and spatial heterogeneity rather than reproducibility between independently manufactured electrodes. The results demonstrate the feasibility of SLA-printed copper-plated electrodes for EDM and identify coating uniformity, adhesion and thermal damage as factors affecting dimensional stability and service life. A solid copper control was not tested under identical conditions, so no direct experimental comparison of machining performance or wear resistance is presented. Seven residual thicknesses determine the deposition parameters, and three working-surface thicknesses determine two effective EDM parameters; all ten locations are calibration data. The mean absolute relative discrepancy is 1.47% for the working locations and 4.42% for all locations. These are fitting metrics. The calculated cavity depth of approximately 8.4 mm and steel removal rate of approximately 35 mm³/min have not been independently measured. Numerical verification and sensitivity analysis are distinguished from independent experimental validation.

The fabrication of tool electrodes with complex geometries remains a major technological challenge in electrical discharge machining (EDM). This critical review analyzes a hybrid strategy that combines additive manufacturing of a polymer core with subsequent electroless and electrolytic copper deposition to obtain electrically conductive tool electrodes. The principal 3D printing technologies—FDM/FFF, SLA/DLP, SLS, and PolyJet—are compared for polymer core fabrication. By the considered criteria, FDM/FFF and SLA/DLP show the greatest practical potential for polymer cores for subsequent metallization. FDM/FFF offers equipment/material availability and process flexibility; SLA/DLP provides lower surface roughness and higher dimensional accuracy. FDM parameters – layer thickness, nozzle temperature, infill density, and build orientation – are examined for effects on geometric accuracy, surface roughness, and thus metal coating adhesion and uniformity. Primary metallization methods (electroless deposition, physical vapor deposition, conductive pastes) and subsequent copper electroplating are analyzed. A synthesis of experimental data shows that in most studies that included a comparison with a solid copper tool electrode, electrodes with a printed polymer core (mainly ABS) and a copper coating provided comparable material removal rate, wear, and machined surface roughness under finishing and semi-finishing conditions; at the same time, in several studies the hybrid electrodes were inferior to solid copper in material removal rate or wore 1.1–2.8 times faster, and data on the service life of the copper shell are lacking. Optimizing FDM parameters and selecting a metallization method should be treated as interdependent stages of an integrated process chain determining hybrid tool electrode performance.