The whole thing was made by taking an old CD covered with a paper, onto which the yoghurt cup was, surprisingly, glued upside-down. Basing was done on top of the "bunker" to give it a more natural feel, and craft putty together with deco stones were used to make the rough terrain around it. Small sheets of plasticard (though paper could have been probably used) were glued and pinned to the cup to make window and doors. Finally, it was painted.
The result is a pretty nice, though small line-of-sight blocking terrain usable as a building for small squads. I was thinking about adding some freehand or decal identification numbers on the side, or perhaps even an aquila... Though I haven't decided in the end and moved onto other projects. I'm still thinking about making more of these and perhaps adding some larger terrain pieces (barricades, fortifications or even trenches) to make a larger warzone terrain set. Hmm... I'll better start stocking the yoghurt cups.