Sci-fi crystal outcrop scatter terrain (scratch built)

Rocky outcrops seem to be a staple piece of scatter terrain for all sorts of skirmish gaming. I've wanted to try may hand at crafting crystal terrain for sci-fi gaming and role playing for some time. I have never tried any sci-fi skirmish gaming so I though this might kick-start that with a bit of cool and adaptable terrain.

Here is a quick summary of the project!

The The base structure is built out of 30mm and 50mm XPS insulation foam from Kanuf. I used the 30mm for the base and (a combination of both for the crystals. 

The cutting was all done with a craft knife with a new blade so as to minimise tearing. The best result visually is achieved if you have an odd number of crystals per base and a range of sizes - I didn't always follow this rule, though! I used angled cuts with the knife to give texture to the edge of the base and to great some cracks in the crystals (see below). 

Then, I applied a stone-like texture to all the surfaces (before gluing) with a ball of aluminium foil. The crystals were hot glued to the foam base and in some cases I used a toothpick to help reinforce the join.

The whole piece is then coated with a sealing coat of Matte Mod Podge with black acrylic paint. The mix is roughly made up as follows: 4 parts Matte Mod Podge to 1 part black acrylic paint. The ratio is not critical - just use what looks good to you. I left these to dry completely. It looks glossier in the picture below that it does in reality.

The first top coat is a dry brush with Mont Marte Emerald Green for their Dimensions acrylic paint range. You can use any cheap paint you like but I did find this colour was particularly good for this project. I left a fair bit of the black undercoat showing through - especially in the thicker sections of the 'crystals' to create a sense of shadow and lower opacity.

Next, I applied a black wash to all the surfaces using a mix made up of approximately, 20 parts water, 1 part black paint, 1 part acrylic medium and 3-4 drops of dish washing detergent (see below). This must be allowed to dry completely.

Finally, I mixed about three lighter shades of the Emerald Green and blended them out towards the edge, leaving the centre pretty dark to give a sense of depth. The edges of the crystals were then picked out with white (especially where they intersect).

Here's a couple of shots of the final product with some Eureka Miniatures 1980s US minis in NBC gear (painted for post apocalyptic gaming).