Volume in in NX10 cam

Hi
I need to measure volume of a body after every step during a milling process. For explm. as you can see in the Image- i want to drill two holes in a solid cube one after another and in between i have to measure how much volume i have deducted in each step.
I have tried to save as IPW part, but i cant do anything rather than visualizing.
Have anyone an Idea. thanks in advance.