I'm trying to make a small indented panel on this model based on the shape I've drawn (points highlighted):



I've tried to construct a curved shape on the surface both using the "Project" construction and by extruding the shape up and using the "Isect" construction (with the plan being to then extrude that shape slightly inward and subtract it), but both of them give me a shape that does not extrude with caps (it just exists as an outline, forming a sort of "duct" when extruded), causing the boolean operation to do nothing.


(This is the opposite direction of the way i'm trying to do it, for clarity.)