For the fans, once you've painted them metallic, here's a trick.
Add some India Ink to Future - and brush it on, make sure to break any bubbles. Let it settle into the recesses, it will concentrate in the low areas and against raised details. It sucks down well. Then dullcoat. Ink glazing works for lots of stuff - like wheel wells - but remember it follows gravity, so you may need to tilt your parts if you want a shadow effect.
http://www.flickr.com/photos/ter-or/3818873253/
http://www.flickr.com/photos/ter-or/220796...57603704701438/
http://www.flickr.com/photos/ter-or/202405...57603176270104/