Wow, thanks for the multiple compliments! I appreciate that a lot, it's a morale booster haha :D So I'll try to explain how I got the metal effect: just add some background layers for darker shades (gradients of 2 or 3 different grays look great) and then add brighter (white, light gray) shapes for the shiny effect. The trick is to add a gaussian blur effect on the latter, so the colors display in a smooth, realistic metal effect. So basically it was made using the following tools: pen, gradient, transparency (to make it even smoother) and layer fx, nothing else.
I know it seems a bit confusing but after all it isn't, it's just a matter of patience and getting the right gradients/shades in the right place.