How would I mask just one arm of the model which rests against another arm and her tummy. I can mask the outside of the arm but when I pull away the underside stays attached as I could not reach there to mask it. Is there a good method to to do this? I just wish to move the arm down to her side. Thanks!
If the two arms have different polygroups, you could select/mask one and then move the other one. If not, you can use the Move Topological brush to gently move one of the arms away from the other.