Thanks guys,
Sure Nitpick.
1) I made the hills from fluid XPS foam, you know the spray can stuff, spraying it directly onto 3mm MDF board which I took from the back off an old ikea wardrobe. Left it to dry.

2) Shapes were cut the usual way and the texture created with a layer of polyfilla (fine powder cement filler). While still wet I mixed in different shapes and sizes of rock and slate and finished with fine sand. I found it effective to shape the hard foam with my fingers (before texturing mind you) to get rid of sharp edges and the like. Also the foam had made interesting cave like formations underneath the surface so I cut the side of the hills to make these caves more visible. I'll take some close ups next time around.
3) Primed the hills black and then airbrushed coats of umber, mud and sand for dirt and dark sea grey for stone areas. Picked out rest of the rock with a brush.
4) I need to drybrush and shade both dirt and rocks and add foliage/flock/tusks for vegetation. Then they are finished. I have 4 hills more on which I'm building ork structures.
Hope it was useful. I thought I had pics of in between step 2 and 3 but alas...
More pics:


