One Blue Personalized Onesie. Choose from 6, 12, 18, or 24 month sizes. Celebrate a special first birthday, thrill a mother-to-be, or complete your little one's outfit with a Blue Personalized Onesie! Simply enter the child's name in the 1st Line of the Product Options to the right, and we'll print it on the onesie in white vinyl. Be sure to browse our fantastic selection of themed tableware and decorations in our Baby Shower Supplies and 1st Birthday Party Supplies.