Here's the Redoubt after it has been trimmed  - this is best done with a large, sharp pair of scissors as the plastic is quite strong. As you can see in the images (right) the redoubt looks great "as is" with some battle damage but I wanted the damage to be a bit more severe and I wanted there to be more of it. I also wanted to remove the doors.

The next step was to attack the model, I used a combination of scissors, an exacto knife and a small drill to remove all the damaged areas and enlarge them. I also added many more shell and bullet holes, the latter in a strafing pattern across the model. Finally I cut cracks and removed corners from anywhere where the model was going to sit on cracks in the terrain.

Next I added rubble by blobbing and painting pva over the model before adding scatter of various sizes from 3 - 5mm bits of plaster to coarse and medium ballast to fine sand, in that order.

A last, and important stage was to the seal it all under a good couple of coats of vallejo polyurethane primer. This protects the polystrene bits I'd added.

Time for a pause and a breath ... at this stage it looked OK and fitted nicely into the terrain. Well, I thought so ... you can make up your own mind, here it is on the left.
I did consider leaving it black, mostly because I'm lazy, but it was a present so I  wanted to make it pop out a little and I just can't help "doing a bit more" with these things (often with disastrous results).

On the right I've airbrushed some old GW boltgun metal that I'd thinned with water and added a few drops of vallejo's flow improver. I tried (with little success) to avoid the bastions and damaged areas.

On the left I'd gone back over, using a brush, the damaged areas, the interior and the bastions with Abaddon Black.

Next (and on the right) I masked off the bastions and brush painted them with retributor armour. Then (far right) masking off and a first dry drush of a dark grey over the rubble and damaged areas.

To finish the model added a wash of agrax earthshade into the damaged areas and rubble (not sure it made much difference) before I dry drushed these areas with three more (increasingly light) shades of grey -  achieved by adding in a little light grey to the previous mix each time. I also dry brushed mithril silver onto the corners and edges of some of the damaged areas.

The plan for the board itself was pretty simple, I was going to use the polystyrene packaging (that the GAMEIN5D boards were posted in) to make "rafts" of basalt that would look like a broken up landscape of solid rock over a barely molten (but very, very hot) layer beneath. The gaps between the rafts would be where the joins in the boards would be, some layers I might build up and others I might cut down.

So, on the right, I've glued (pva left overnight) all the basalt rafts (sounds better than polysytrene pieces) and sprayed everything with Vallejo's black acrylic primer. This protects and strengthens the polystyrene and means I can use solvent-based stuff if I want later. I've also built up some areas with double or more layers to create a topography.

 At this point I also decided it was looking a little boring with all those flat, black slabs so I started to carve out some cracks with the idea that these could bring a bit of colour across the board as well as break up the parallel and perpendicular lines necessary because of the joins between the boards. This of course assumed I'd be any good at painting lava . . .

As it was quite a large area to dry brush I used some cheap acrylic paints, Crawford & Black and Pebeo (neutral grey). I also used cheap and quite large brushes and a big piece of cardboard (all pictured, right) to do mixing. Quite simply I mixed grey into the black in increasing amounts as I worked higher up the levels in the terrain, the higher up the paler the grey.

 I was quite happyIn the photo on the right only the lower  tiles have been drybrushed and you can really see the contrast between those tiles and the unbrushed tiles above.

I took some time to work all around the board and I had to go back and darken some areas are I got a bit carried away (or stopped concentrating.

I then broke out the airbrush and painted all the gaps between the rafts in GW's Khorne Red (air) . I didn't try too hard to get the red into the edges of the rafts as that left some shadows but also I didn't mind a bit of red going to the sides of the rafts to give them some glow from the hot ground.

In the end I settled on laying down a thin layer of GW's blazing orange which I'd thinned down for airbrushing before dropping the pressure on the airbrush so I could add a thin line of yellow (in this case Vallejo's sand yellow, 70.916). This seemed to produce a glowing effect that I could live with as shown on the right.

I'd read about using pva to produce a crackle effect for lava so I thought it might be fun to try that in a couple of places. It's a bit unpredictable but I found airbrushing black paint (as thick as you can get through the airbrush) over pva that had been left for a little while to go tacky seemed to work ok, the picture on the right shows on of the better bits.