Imperial Bunker

I had a little time off from unpacking boxes (after unpacking 6 of them I thought I needed a treat), so I assembled the Imperial Bunker from the Wall of Martyrs buildings.
This was quite easy to fit and glue together, but it'll be a small nightmare to paint with all the details around the building walls. There is a lot of dead Imperial Guard troops and wrecked equipment, and this needs to be painted in its original colours and then weathered to look old and ragged.
Not really sure how ceramite (or what ever the Imperial Guard helmets are made of) degrades with age, but I guess I'll think of something.
I know I will paint the helmets in a few different colours to show that there has been many battles fought around the bunker, and that many different Guard units has fought there over time.

The bunker walls will probably be sprayed with black base spray, just like all the buildings that I create from the Imperial Sector buildings. But when I was at Games Workshop in Oslo on Tuesday I got a tip not to leave the walls just sprayed that way, but to drybrush them a bit with grey. So I will do this, and then paint all the details. Hopefully this will make it look both like real walls, and fit the look of my bases.