Hi Jesper, it's looking great! Currently there is nothing set up in MoI to do volume calculations, but that is something I want to add for v3.

At the moment though you would have to export your model to some other CAD program and do the volume calculation over there. One pretty inexpensive CAD program that can work well to help out with various things is ViaCAD: http://www.punchcad.com/p-9-viacad-2d3d-v8.aspx

- Michael