You can make certain layers export as non printable layers when exporting from Revit 2012 to AutoCAD DWG or DXF files.
First, you need to set the following checkbox in the Modify DWG/DXF Export Setup dialog box:
|Make layers containing the following text non plottable NPLT|
Then, make a line style and map its layer to a layer name containing the text ‘NPLT’:
After the file has been exported, you will see that the layer has been set to non printable in the AutoCAD Layer Manager: