You can extract (copy) outline edges or 3D intersection lines (curves) from any 3D solid or surface models in AutoCAD.
This can be done with the XEDGES command, where you just select a 3D solid (3DSOLID), 3D mesh (3DMESH) or 3D surface (SURFACE) object. Its edges (wires, wireframe) are extracted as new simple entities in 3D - lines, arcs or splines (as neccessary - from the geometry shape).
If you want to get the 3D intersection curve of two separate 3D solids (e.g. a conic section), first convert these solids to a single body - e.g. with the UNION command.
If you want to extract only a selected edge, use the command OFFSETEDGE with the option Distance = 0.
The extracted geometry may be obscured by the source object so you may need to delete or hide the object.