are you sewing them or using elastic thread? I use 42 strands of 2 inch peices and tie them off with elastic cord. I go around them 3 times with the cord and they hold so tight that you couldnt pull a single strand out even if you wanted to
sometimes when I dont tie them off exactly in the middle I get that blob effect, but this is what I do, working from the top, seperate the peices strand by strand, pulling them gently in a upward motion to seperate them and get that "poof" look. Hope that makes sense.