Diego Martinez outlines a 5-step process for redesigning student lockers at a high school: 1) Understand the current problems with lockers by talking to students, teachers, and staff; 2) Define the requirements of new lockers through conversations with end-users; 3) Design lockers that meet user needs and fit the space; 4) Propose locker prototypes and present designs; 5) Implement the selected designs, evaluate their use, and make changes if needed.