Thanks, the aluminium element was cooked and sandwashed, then I used black powder paint, you have to be careful though because inside there is a tiny hole for a screw. You have to watch not to paint it over because powder paint is fairly thick and you could fill the hole with it. No base paint needed, sandwashing gives you a texture so the powder paint sticks and holds well, it doesn't fall off the black element but the red ones. All other elements (grills, volume rockers, power button, battely and simcard covers) are painted with red spray carpaint. You have to be careful with it as well, you need to add a very thin layer of translucent paint over the color to prevent the paint from falling off. I didn't do that and have to redo all the buttons, paint is coming off. You can't sand those elements because they are either too small or plastic and sanding would destroy them. With spray paint you have to put thin layers and only few of them (2-3) because every layer of paint makes the element thicker and in consequence the whole phone will be harder to put back together.