Partially opened tops like the Ulitize stuff? Sadly, that need to be designed into the original mesh. On the Ulitize tops, the mesh isn't a closed cylinder - at the front the mesh doesn't join up, more like a roll of paper, so to get the open morphs all you have to do is pull the two seperate areas away from each other. It's a nice idea, and I can see how to do it in Wings (my modeller of choice), using the hole material to break the solid object, but sadly it's too late for this dress - Wings doesn't seem to cooperate with the UV mapping on imported obj files. That might become the project after next (kimono style dress in very early development, then perhaps a proper opening blouse.)