You probably own a ton of gadgets made from aluminium and titanium. A lot of 'em by Apple. But did you know that the smooth, brushed finish on the surface of your MacBook or iPod is actually made with a thin level of rust?
EngineerGuy Bill Hammack explains that the finish is achieved by oxidising — or rusting — the aluminum on the surface, enough for dye to seep into the tiny holes created by the process. The metal seems painted, but the colour actually becomes part of the aluminium. It's pretty cool, and another way that Apple and other bright-and-shiny makers get creative with engineering when it comes to design. [YouTube]