Cut lots of squares of HEAVY-DUTY ALUMINUM FOIL. Apply to surface with wallpaper paste, and flatten the foil with a spatula. Make sure you always get the shiny side up. Overlap the edges of the foil. After it’s all dry, use damp rag to wipe off the glue residue. If you want, apply black acrylic paint to the foil’s wrinkles. Apply two coats of Minwax Polycrylic (for metal).