CAD tip # 13056:

If you want to copy properties (including custom properties) after that, between existing drawings, use the Express Tools command PROPULATE and its PRP template mechanism.

1. Open the drawing containing the source drawing properties.
2. Enter the PROPULATE command and its "Edit template" option.
3. In the "Edit Propulate Template" dialog, expand the Template menu and use Fill from Current Drawing. This will fill the property fields in the template for subsequent copies.
4. Fill in the other required information in the template properties window.
5. Select the Save As function from the File menu, name and save the .PRP file (e.g., into your Documents folder). Exit the dialog and the command.
6. Now open the target drawing into which you want to import the properties (it has to be saved at least once).
7. Enter the PROPULATE command and select its "Active template" option.
8. Select the pre-saved PRP file and confirm OK.
9. Confirm the "Update" and then "Current drawing" options in the command options. This completes the property transfer.
10. The transferred drawing properties, including custom properties (their definitions and values), now appear in the dialog after entering the DWGPROPS command.