how did they make zero in nightmare before christmas

In "Nightmare Before Christmas," Zero the ghost dog was created using a combination of animatronics and computer-generated imagery (CGI). The animatronic head was created using a combination of clay sculpting and computer design. The designers built a life-sized model of the character, which they then scanned into a computer to create the 3D digital model. This model was then used to animate the character's movements and expressions using CGI software. Additionally, the animators added digital effects to create the character's glowing eyes and mouth.