There's some vanity feature you're meant to unlock at level 5, but it isn't in in Beta 4. I posted a thread about it here and the devs didn't elaborate on it, so I have no idea what form the vanity feature will take. People have suggested stickers as well as painting. Personally I'd prefer the dropship level 5 one be changing servo colours in some way and level 10 be stickers (level 9 reward as the 3rd servo class?)

Make them custom stickers so I can put this on my squad