Superhero themes have been increasingly used in the teaching of a range of topics including business, humanities and science in recent years. Typically, characters from existing popular media are adopted for the teaching activities. On the other hand, customised characters that are developed from scratch allow the educator to have more control of the characters' features so that the learning objectives can be achieved more effectively. In this work, new fictitious characters have been created as cases for students to perform their engineering materials selection assignment. The motivation for using the superhero theme was to increase the students' excitement in the assignment. This paper shares the approach taken and the teaching experience after running the superhero theme with two cohorts of students.