I can tell you from the years of experience I have that framework (i.e. interfaces) are very difficult to do if you want it to look good.
www.phoenixium.com check out this site for an example of a painterly metal style (which I think looks the best)
this is done through a simple two color high contrast scheme and two highlights (a direct light gleam and a secondary light gleam)
if you understood that, the frame is cake