Load the disk sander with a 60-grit disk.
Lay the copper sheet face down on a sturdy surface.
Turn the sander on and apply it to the sheet, creating a pattern of circular etch marks across the entire back surface.
Turn off the sander.
Soak a rag in lacquer thinner and thoroughly polish the newly-etched surface with it. Give the surface 30 minutes to air dry.
Pour 3M Fastbond 30NF liquid adhesive into an empty 1-quart paint can until the container is two-thirds full.
Dip the paintbrush into the liquid adhesive and paint a thin layer onto the area of the wood where you plan to attach the copper sheet.
Paint a thin layer of adhesive onto the entire etched surface of the copper sheet.
Lay the copper sheet on top of the wood so that the two adhesive-coated surfaces meet.
Lay a sheet of 4 Mil. plastic sheeting over the entire copper sheet.
Lay a sheet of 1/8"-thick cork on top of the plastic sheeting.
Lay the batten over the center of the cork sheet.
Attach a G-clamp around the top of the batten and bottom of the wood every 8 inches.
Tighten each G-clamp snugly.
Remove excess adhesive from around the edge of the copper sheet.
Allow the assembly to dry for at least 12 hours.