1/8" thick aluminum plate. Glued to the face of a used 4-CD slider tray, which I sacrificed for the cause.
Mark the gauge locations on the aluminum, and then cut away everything in the CD tray which falls within the circles. All that is left is the mounting brackets at the edges, so that the tray / gauge holder slides in and fits into the console the same as it did when it held CD's.
Paint face of aluminum with matte black spatter spray paint, found at hardware store, for a bit of a textured finish.
