Hello
We have exactly this kind of need. But the "dynamic" nature of the BOMs in Windchill (ConfigSpec, effectivities, xBOMs) make this need difficult to handle ...
For me the best way, is to build a Cognos report that will summarize weights, or a dynamic calculated attributes ... based on part structure and a configspec ...
because the result will depend if you want the weight of the latest Released EndItem BOM, a particular baseline or lot number ... or the latest work in progress one ....
Difficult to persist this kind of information , as You don't want necessary modifiy or iterate each End items when you change a component in the sub/sub level of the structure ....
regards