From Nevercenter 3D Modeling Wiki
Default Shortcut: Ctrl + C
Menu Path: Edit > Copy
The Copy command will copy whatever shapes, faces, edges, or vertices you have currently selected to the clipboard. You can then use the Paste command to create a new shape that has the same structure as that which you copied to the clipboard. You could, for example, copy a sequence of edges from one shape, paste them to make a new shape, and then use that new shape as a path for a Path Extrusion Object to make an extrusion that exactly follows the contours of the original shape.
- Also see Paste.