Personalized Mechanical Engineering Genius Toddler Long Sleeve T-Shirt. Mechanical engineering genius text with a line of gears is a unique gift design with attitude for engineers and students at back to school, birthdays, holiday and graduation. A classic for Fall, Winter and Spring, these long sleeve toddler t-shirts are sure to be a staple in your child's wardrobe. Whether layered or alone, this t-shirt is soft yet durable enough to stand up to your toddler's playtime demands.