My company uses a number of alloys and budgets there use based on weight.  Our "parts" are actually built in Solid works as assemblies where each solid works part is one part made from one of the alloys.  I have the alloy type set as a custom property and set the density to match.  The part alloy and mass display in the assembly BOM.  My question is how do I sum up the total alloy weight of all the components of the same alloy?

Thanks much