I have raised the issue that shelling and offsetsrf are critical for 3D printing.
One observation with the Shell command is that it does not handle situations [well] where opposite sides are close together such that the inner shelled surface needs to be far away from the outer surface.
In my ship hull, the opposite faces of the twin keels are closer together than twice the offset distance.
Rather than just make the twin keel solid, Rhino pushes inner face it creates outside the surface I am shelling.
This is not an exclusive Rhino problem, many solids modelers would fail in this situation.
Can you post this file and indicate the offset / shell thickness desired? … ShrinkWrap would most likely help here since it uses voxels and is not subject to this limitation.
Interesting that you meant that. The first version I made for 3D printing was using ACIS. ACIS had no problems shelling any of the parts. With ACIS shelling and creating plans (Make2D) worked flawlessly.
Fortunately, my list of “ACIS is better” is limited to those two items.
I would be willing to try this object in SolidWorks for a comparison if you are interested.