To skin weight paint 3D models for VTubing, bind the model to a rig, then use a weight paint tool to set each bone’s influence on vertices—prioritize smooth deformations for natural facial and body movements.
Weight painting controls how the model moves with the rig—key for VTuber animations like blinking or arm swings. Focus on gradual joint transitions (elbows, knees) to avoid "pinching" and precise facial control (mouth, eyelids) for lifelike expressions.
For beginners, use symmetry tools to speed up work, test animations frequently (e.g., jaw/arm movement) to fix uneven weights, and start with simple models and basic rigs (10–20 bones) to practice.