Export Surfer contour map to 3D DXF for display in AutoCAD

1. Create a contour map by clicking Home | New Map | Contour, selecting your grid file and clicking Open. You can select the contour map and adjust any of the properties (such as the contour interval) in the Properties window.
2. Once the map is the way you want it, select the Contours layer in the Contents window and click Map Tools | Layer Tools | Export Contours.
3. Give the file a name and choose AutoCAD DXF File from the Save as type list. Specify a location for the file, and click Save. The 3D DXF file is exported with the Z values for the contour lines. 
4. You can use this DXF file in AutoCAD to create a 3D surface. For example, in AutoCAD 2019
   1. Double click the open file icon in the top left corner of the application (), change the Files of type selection to DXF, select the DXF, and click Open.
   2. Click the  icon at the right side of the application.
   3. Click in the lighter gray box around the darker gray "Top" box.
      
      This will project a 3D version of the DXF file. You may want to click and drag the 3D box to rotate and tilt the display to a desired angle:
      

Updated August 26, 2020