Im making my model in NURBs, I like them and Im sick of using polys for the last 2 weeks.

To cut out your indentations; create two circles and project them around the middle of the surface. Then trim out the middle part. Create a cylinder for the lower indented surface and a flat circle for the top and bomttoms of the indented surface.

Alternatively, just insert isospams and cale them inwards.