one puzzle piece is a cartoon character, with two arms and two legs, it has eyes and a mouth, it is made of thick cardboard, protruding parts on the left and right and on the top, a trailing part on the bottom.

It sounds like you're describing a puzzle piece that resembles a cartoon character! If the puzzle piece is designed to represent a character with arms and legs, eyes, and a mouth, it could potentially be a playful, anthropomorphic character. The protruding parts suggest that the cartoon character might have features like ears or hair, while the trailing part on the bottom could represent legs or a tail. Using this description, several characters come to mind that might fit this appearance, especially from children's shows or cartoons. If you're looking for a specific character, could you provide more details about the colors, patterns, or any additional features? This would help narrow down the possibilities! If this is a creative design, you might consider what personality or theme you want this character to embody.