I have drawn a piece of 2” x 2” x 3/16” tube steel. I drew a rectangle and extruding it filleted the sides and shelled it. I did not find tube steel in the materials library so I crated a new material. The weight should be 4.31lbs per linier foot which I converted to cubic inch in the new material. However, when I check the mass properties the value is way off. It looks like it might be adding the inside surface area as well. Anyone have a suggestion on how I fix this?