Help with finding mass of part

Hello!

I am currently modeling a part as an exercise for a CSWA course that I am taking. Unfortunately, I seem to have become stuck with finding its mass as the answers I am getting are incorrect. The part uses copper as the material, is modeled in IPS, and has an arbitrary origin. I have attached the screenshots of the part drawing views as well as my attempt at creating the part. I am supposed to provide the mass in lbx10^-3 and round to the second decimal place. I would appreciate if anyone could take a look and see where I went wrong and give me an explanation about any errors I made as I would like to learn from this and not just have the right answer.

Thank You!

SolidworksGeneral