Father and son Louis and Nate Peters are working on a one-of-a-kind Halloween costume for one very special little girl.The family duo was introduced to the family of 9-year-old Kathryn Thornsberry, who has cerebral palsy, through the nonprofit organization Magic Wheelchair. The two builders volunteered to design a custom costume that would fit Thornsberry's wheelchair perfectly and be the envy of her peers on Halloween. Thornsberry is a fan of the popular "Minions" from the "Despicable Me" animated films, so the Peters got to work building her very own "Minion Mobile." The costume was made from scratch by the father and son team, who hope their act of kindness encourages other builders to help kids like Thornsberry.Watch the video above to get a first look at how the Minion Mobile is being built.