Determine the location of your melamine joint. The first board has a groove cut. The second board is fashioned to fit into this groove at a right angle.
Set up the router table fence to make a dado cut in the selected location on the first board. Cut a 1/2-inch-wide dado, the width of the melamine board. The depth of the dado cut should fall between a third and half the thickness of the board.
Adjust the router fence to make a rabbet cut along the edge of the second melamine board, 1/4 inch deep. Set the router bit depth to cut a 1/2-inch-wide rabbet tongue.
Dry fit the rabbet tongue to the dado cut. Once the fit is satisfactory, apply melamine glue along the dado cut. Fit the rabbet in the groove. Wipe excess glue with a wet rag. Wrap masking tape around the two pieces to keep the rabbet firmly fitted while the glue dries.