Start by cleaning the surface with a mild detergent and water. Dry it thoroughly. For scratches, sand lightly with 400 grit paper, then wipe. If the paint is flaking, fill with a thin layer of body filler, sand smooth, then repaint with a matching gloss. For parts that rust, use a rust remover, then apply primer and paint. Polish with a metal polish to bring back the shine. Keep it organized and tackle one section at a time.

Look for a lightweight epoxy filler like J-B Weld's Quick Cast. It’s easy to shape, sets fast, and stays rigid once cured. Mix it with the included hardener, apply with a small spatula, let it set, then sand and paint. It won’t warp if you keep the fill level low and avoid over‑loading the thin parts.

Just lay the filler in a thin, even layer and let it cure fully before sanding. Once it’s set, you can scrape off any excess in one smooth pass. That’ll keep the hinges clear and prevent any warping. Good plan.