I have tried to make an acrylic skin a number of times in the past. I was never successful as I didn't have the right substrate. Yesterday in a workshop at Sandra Spagnuolo's she provided a 6mm vapor barrier plastic. It worked great. The skin pealed off it in one whole piece. It's possible that using a good quality acrylic paint on the first layer made that easier. I used cheap acrylic paint for the last layers as you don't see them. You just need them to build up thickness.