Personalized Smart Mechanical Engineer Youth Long Sleeve T-Shirt. Mechanical engineering, the profession for intelligent people text with the E in engineering wearing a hard hat, is a humorous design with attitude for college students and engineers at back to school, birthdays, holidays and graduation. youth long sleeve t-shirt. Shoulder-to-shoulder taping. Youth: S(6/8), M(10/12), L(14/16), XL(18/20)