You could take the mass data from the flat state. The flat pattern feature has the option to flatten all forms. Actually, this would make for a nice improvement where one could switch the mass properties (volume) to read the volume at the flat pattern feature (since this is -always- at the end of the tree) if it exists. A simple smtl config.pro option would manage this. Or provide a separate mass property entry for the flat pattern state in the software. This one should be very easy to implement if anyone can decide on the best way to handle it.
if you can, vote here: Calculate sheetmetal mass properties in the flat pattern state
