Painting them was a lot of fun, and the base white surprisingly simple once I got some advice. It's basically a spray of black followed by one of white a few seconds later to get a gradiated grey effect. Once that's dry I gave it another dusting of white spray. I then mixed up a pot of Citadel Lahmian Medium with a dash of Agax Earthshade and gave them all a liberal washing down. Lastly, a white airbrush to the helm, shoulders and knees gives a nice spot highlight.
The weathering is simply tiny dabs of Charadon Granite applied with a bit of torn off blister foam.
The red is achieved by applying a base of Runefang Silver, then two washes of Forge World's Angron clear red airbrush paint (brushed on, not airbrushed), then silver chipping and finally a wash of Agax.
The golds are a base of Citadel Retributer Armour, washed Seraphim Sepia, then layered with Liberator Gold and highlighted with Runefang Silver. The two new golds are incredibly dense in pigment so i recommend them very highly!
Lastly, I gave them a high gloss varnish and then applied decals and any final washes (as washing over gloss breaks the surface tension and pushes the wash right into the recesses without covering the rest of the surface). Once the decals were on I scratched them up a bit with a scalpel to push them back into the surface and weather them, and finally applied a satin spray varnish.