Select the 3-D objects or regions for which you wish to perform mass calculations. Hold down the "Control" key and click on multiple objects, if you wish to calculate the mass of multiple object or regions on the same plane.
Click on the "Tools" menu, and under the "Inquiry" item, select "Region/mass properties." Alternatively, if you use the command line, simply enter the word "massprop."
Read through the mass properties generated in the new dialog box. The mass calculations will include numbers like "area" and "perimeter" for all regions, as well as more precise numbers like "mass," "volume" and "moments of inertia" for solid objects.
Click on "Yes" or type "y" when the program asks you if you want to export the calculation values to a text document. Enter a name for the document, select a saving location and click on "Save." All the numbers can later be retrieved from this location.