So my first setup was pre-made, I decided for my second to try and do it myself. So far I have done the polystyrene base and the foam coverage. Pretty pleased with it so far! Should have made the bottom "cave" a bit deeper but nevermind! Will be covered in resin and then covered with peat - will upload pictures when I've done that! It's a 40x40x40 tank with a sloping false bottom that drains into a gully at the front.