Interior geometry

Is there a method to find/create the interior volume of an existing V6 object? We have multiple hollow objects to sandcast and we need cores to do this type of casting. If the interior geometry can be made and 3D printed, a core box can be constructed to make sand cores. Thanking all who provide info.

Dear @franktrueblue
is it mesh, nurbs or sub-d data ?

for polysurfaces / nurbs the basic command is
_offsetSrf
and maybe
_shell
Rhino is not the strongest cad-package when it comes to create material thickness.
if the geometry is very complex or has complex filleting rhino will fail.
can you post sample data ?
it is not possible to precisely answer your question without this context. What is the desired offset, the tolerance, the details, the object-type.

hope this helps to get your question more specific.

kind regards - tom

Tom, thanks for the speedy reply. The originals are modeled in Rhino, so nurbs. The geometry is not overly complex. The desired wall thickness will be from .100" to .200". The outer original surface has lots of detail but the core shape should be smooth and follow the outer surface by the thickness. Originals are customer proprietary. I’m thinking _offsetSrf will try to move the detail onto the interior surface, which would be detrimental. For example picture a 3D rooster with detail down to feathers. Need that interior reduced by the wall thickness, without the feathers. All orginals are highly organic in design. Would a mesh approach be better?

yes _offsetSrf will try to keep all possible details.
if you want a rough estimation within a tolerance, an approach might be via mesh or voxel.

other workflows might include:
defeature / defeaturing
enveloping
ball pivoting algorithm for mesh

and don 't forget manual craftman-techniques to do the core / internal mold. - like termporary applying a layer of clay or wax

it is really funny, that you mention feathers of a rooster - i was responsible for the 3d-Data of the Hahn/Cock project by Katharina Fritsch