I was wondering how people normally do a complex core design. My situation is this: I create a part that is fully drafted and essentially hollowed out by a core on the inside. The core is like a shell of the part but not exactly a shell entirely. And I need to actually do a bit of design to the core itself for the tooling and the core print etc and doing the filleting. So it will have to be split from the main part from which it is derived. What I have been doing to make a solid body from the volume of space produced by the core is to make a surface body and then knit it into a solid. The problem being is that if you create a core using surfaces off of the actual part, when you make a change to the main part it generally does not update well to the surface model from which the core is derived, especially if you have a moving parting line.

I was thinking I could use a cavity feature, but the parting surface for the part and the parting surface for the core are not the same so if I split the part at it's parting surface and then use the cavity feature I will not be getting an imprint of the core that terminates at it's parting surface.

I hope I am explaining this in an intelligible way.

Any tips for complex core design?