One Train Personalized Onesie. Choose from 6, 12, 18, or 24 month sizes. Dress up your little engineer with our precious Train Onesie, personalized with your child's name! This cute red onesie features an adorable white choo-choo train and white lettering. Simply enter your child's name in the 1st Line of the Product Options to the right, and we'll print it below the design on the onesie. If you're celebrating a birthday, be sure to browse our fantastic selection of Train Party and 1st Birthday Party Supplies to coordinate with this Train Personalized Onesie!