"Silver" and "gold" coating a 5 cent coin

Last Friday, I coated with my kids 5 cent (copper) coins. They look pretty nice even though its only zinc and brass. All you need is a clean copper coin (you can clean old coins efficiently with vinegar), sodium hydroxide (NaOH), zinc powder and a hot plate. The original method (see this PDF) uses a bunsen burner, but we did the heating and the final conversion of the zinc-plated coin into a brass-plated coin simply by placing it on our kitchen's hot plate. Hot sodium hydroxide is pretty dangerous, so be warned (eye protection) and keep the kids under control!