I've been thinking about a new tool

I would like to make something that could certainly help mappers.
A little thing that would tell us how much space remains to use embedable objetcs once we have already choose some for a map.
But for that I need to know the weight of each embedable objects, and I don't know how to do with those that are in a .Pack.gbx file.
I think I could ask to objects builders what is the weight of their objects (when in a Pack), but will they be able to answer ?
Is there any solution for that ?