Subtracting parts in Sheetmetal??

In my sheetmetal assembly I would like to subtract one part from another. In solids it works using EDIT-COMPONENT OPERATION-CUTOUT.

This apparently does not work in the sheetmetal application.

Pretty sure there is no way to do it but though I would throw it out there. I need it for doing mass calculations where there is part interference, and the parts MUST be sheetmetal.