TerryS wrote:1. Use Offset 3d Polyline (command: offset3d) and choose the Surface option
2. Use Design Pad Template (command: pad)
Those commands will not do what the poster wants them to do.
The OP wants to extend a 3DPolyline to a surface. Not offset the 3DPolyline.
I suppose one could draw a 3DPolyline perpendicular to the one to be extended and Offset3D that line. But that's a lot of steps to do something that shouldn't be much more difficult than using the Extend command.