I shot each girl separate in this shot. I laid them down, sprinkled flour all over them (making sure a bit of it spilled onto the floor all around them), lit them from lower left and took the shot making sure the lighting/camera angle was the same for each girl. I then set up the background and props, matched the lighting and angle, then took the shot. in the editing process, I made sure all 3 images were edited the exact same way, masked the girls in, then color graded and made my final adjustments afterwards. the masking was fairly easy since the images were shot to match.