Update!

I can finally show the project that had to be kept secret, it was the Void Dragon (or at least a shard of him) for the new Necron army by Games Workshop. I have painted him using SENMM (Sky Earth Non Metallic Metal) which is basically just using blue and brown paints to represent a metallic effect that shows environmental reflections.

I've just uploaded the first video in the series for how to achieve the effect!