It's worth saving a copy of the prop when you get it working right in Poser. (Select the object, open the Prop library, and use the "+" button at the bottom.

Odd thing is, I once had some ballooning on a toolbox model, but it was a sci-fi scene and it looked OK there. Most of the edges were unaffected, but the shape of the lid changed. That's supposed to be a hinge on the side.