Personalized Mechanical Christmas Tree Toddler Long Sleeve T-Shirt. A Christmas tree made of red and green mechanical gears is a humorous holiday design to tickle the funny bone of your favorite mechanic or mechanical engineer any time of the year. 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.