lowercase letters for airpods??

im planning to purchase airpods, and get an engraving with it. i’ve noticed that devices such as iPads could get an engraving with lowercase letters, and upper case, but not airpods. i know that airpods used to have lowercase letters because a friend of mines got engraving on his/hers. is it possible to choose lowercase letters engraved onto airpods and not forced for all letters to be upper cased because i would prefer a upper case then rest lower cases because of the look/name etc. it would really help if you have an answer and respond. thanks !