<p>Glass materials are widely used in optical lenses, micro-electromechanical systems (MEMS), and micro-total analysis systems (µ-TAS) owing to their excellent optical transparency and chemical stability. However, their high hardness and intrinsic brittleness make conventional mechanical machining prone to brittle fracture, resulting in cracks, surface defects, and edge chipping. Ductile mode machining of glass can be achieved using microtools when appropriate tool materials and machining conditions are carefully controlled. In this study, microtools made of tungsten carbide (WC–Co), polycrystalline cubic boron nitride (PCBN), and polycrystalline diamond (PCD) were fabricated using electrical discharge machining (EDM), and their tool fabrication characteristics were systematically investigated. The machining performance of these microtools was evaluated through microhole drilling experiments on soda-lime glass to assess chipping behavior and thrust force, as well as microgroove machining on an inclined substrate to determine the critical depth of cut (CDC). The experimental results revealed that the PCBN microtool exhibited the most stable fabrication quality, whereas the PCD microtool demonstrated superior machining performance. In particular, the PCD tool effectively suppressed brittle fracture, resulting in the lowest chipping and the highest CDC among the tested tools. These findings indicate that PCD is the most effective tool material for achieving stable ductile mode machining of glass materials.</p>