There have been several threads in here on the subject. I have tried forming balsa by wetting it then forming it around a male plug, using vacuum assist. This preformed 1/16" balsa skin was then layed up over 1 oz fabric in a female mold. This was for a turtle deck that had only one axis of curvature, and was not easy. As far as not crushing foam goes, I have vacuum bagged several foam wings, and this is not an issue since this application does not require more than about 6-8" Hg vacuum. I doubt that a molded composite wing requires much more.