What is the command to create a 3D polyline?

The command to create a 3D polyline in AutoCAD is indeed 3DPOLY. This command is specifically designed to create polylines that exist in three-dimensional space, allowing for vertices to be placed at varying elevations. When you execute this command, you can define points in 3D by specifying the x, y, and z coordinates, which is essential for modeling in a three-dimensional environment.

In contrast, other commands like PLINE or POLYLINE primarily create 2D polylines, which do not accommodate differences in elevation. LINE3D is not a standard command in AutoCAD, so it wouldn't create a polyline of any kind. Therefore, understanding that 3DPOLY is dedicated to laying down polylines in three dimensions is crucial for working effectively with 3D designs in AutoCAD.