I started with a big bottle of PVA and the aforementioned packaging, plus a nice 2' x 2' (roughly) piece of blue foam to base it all on. Let gluing commence!
Once the first layer was down, the more mountainous areas.
I picked away at the edges with a scalpel to try to make it look more natural.
Cardboard box full of cat litter holding down the top layer to ensure a firm bond.
Aforementioned cat litter sprinkled on liberally applied PVA (with a bit of water for covering power. My reasoning was twofold - a) the litter would make the flat tops more uneven, and b) as the mod-roc is soaked in water to activate it and it's being applied to cardboard, I thought it might alleviate some sogginess.
I chucked any other uneven bits on there too
So here's the first layer of mod-roc being applied. This is the same stuff as a nurse would use to plaster your arm. Dip in water, and then lay on.
That's the whole thing mod-rocked. Fags for scale.
Spare cat litter used for rockfalls.
The hangar entrance. Gives it a nice 'Captain Nemo' feel, I think.
Main entrance. I smoothed down the area in front as it would be used extensively.
First dark spray - this is spray on stone (yes, it's real, you can buy it in B&Q).
I kept layering it until I was happy
Spray on stone detail.
I popped some covenant buildings on for scale. I'm going to be using these and some firestorm armada bits to make a city.
Some more work with spray blues and greys, white spray highlights, then various snow powders and pigments added for detail. It's looking ok, but it needs a companion board (so that it covers 1/3 of a 6x4 table, a harbour and docks in the middle, and a city built around it. Quite a lot more to do on it, I'll add pictures as it jostles with the umpteen other projects I have going.