Hi
Not sure I understand exactly but if you are getting the mass (output only of course of a part) of a part one can parameterize e.g., by changing the physical dimensions of the part, or the material density used for that part (make density a parameter in engineering data).
ALso another way could be (not sure if this is possible since I do not see a model) to use a point mass (see below), and make the mass a parameter:

All the best
Erik