For the PC-Version: The character-"designs" created in the benchmark are saved in C:\Users\NAME\Documents\My Games\Final Fantasy XIV - A Realm Reborn (Benchmark)

I'm not sure if the actual game will access that folder aswell and let you pick your appearance in the actual launcher, but if it doesnt it should be easy enough to drag the data from that folder into just \Final Fantasy XIV - A Realm Reborn (which is in the same place) and that should work for sure.