Basically is there a way I can zero out all material properties, and assign values to only the ones I want to use in the part? Without linking it to a material in the material library that can affect other parts.

And because I know someone will want to have an example for why I want this; I am making a pattern to be cut out of expanded/grated metal. I know how much per foot it weighs and that is the only property I really care about. I know I can just assign it a weight of say 5 lbs, but I would much rather have that weight linked to the actual shape of the part and not have to manually re- calculate that with each change. Or at least have it be zero so it's weight is not added to assemblies it is used in.