That's pretty much the limit of my Blender knowledge, so hopefully someone else can jump in and help you. There may even be a zbrush or cinema 4d solution, but I don't have any knowledge of using them. The Mad Moder
michael@shapeways.com
Get your self a copy of VisCAM Mesh. 30 days usable test version. It will automatically hollow out your model to the thickness you want. http://www.marcam.de/cms/viscam-mesh.84.en.htmljacantdesign@gmail.com