Another style of Cavity? A way to make a cavity AND keep the piece removed.

Ive currently be using the cavity tool to cut some holes in Mandibles.

However, now that I have an idea of what I am to be doing, I require the hole as well as the piece I have just cut away.

I have been cutting a piece from the mandible, using a cube shaped block and the cavity tool.

This was rather easy to use and it gave me the perfect cut I was looking for.

However I now need the piece I cut away.

Is there a way to cut away everything OUTSIDE the box, like a way to keep the cavity and remove the rest?

That way I can work on the piece I have removed, make a replacement, and put back in a piece that will fit perfectly.

It could be a simple button somewhere I have not seen.

Thanks very much!