Bill was involved in the storyboarding of the film and did a lot of the model sheets, which show the animators what the characters look like in various poses. His infant son, Bill Jr., was a "definite influence in the way I drew the baby elephant."  Bill went on to become Walt's top storyman; writing the scripts, drawing the storyboards, and designing the characters. Bill Peet loved elephants and loved drawing them.

"The thing was, I was a circus buff, so Dumbo was great chance for me to get in and do a lot of boards. That was the first time Walt really noticed my work. Since I knew the circus, and had done so much sketching at the circus, the old big top circus, I just loved working on that thing".