8 XXX : NakedProgress

I don't know what you're currently doing but,(pun intended) it's working out great! Nice improvement! Some exercises that come to mind that work flutes are hip thrust, deadlifts, weighted squats( regular are fine too but you quickly get used to those), lunges, Bulgarian split squats, leg press, variations of glute kickbacks. All those kick my butt most definitely.
This is AMAZING. Just proves the stereotype that white girls don't have booties is FALSE. Great work
Fantastic and just beautiful work! Check out bodyspace.com and it'll customize/recommend exercises based on your body and goals.