- Download unfoldtool.zip.
- Move the file into your SketchUp/Plugins folder.
- Restart SketchUp.
- Select the Unfold Tool from the Plugins menu, start selecting faces to unfold. The selected face is unfolded to match next selection.
- Hold the Control key to reverse operation - rotate the subsequent face to match the already selected face(s).
- Alt-click on a face to select all the faces in the same plane.
- Shift-click to toggle selection of faces.
- Click off the model to reset the selection.
My unfold tool is pretty basic - you may want to check out the Flattery plugin as an alternative.