So the base has progressed.
I shaped the MDF before adding some Milliput to smooth everything over. I added a 'floor' - basically the top of the foundation or something like that - using some foamboard and then used filler to fill the gaps and give a rough end to the floor. Once that was dry milliput was used to give some more texture.
Outside the ruin sand was put down before the rubble was added.
After adding some pipe work rubble was also added internally where explosions would of blasted rubble underneath the ground floor.
For the actual floor I dismissed the original plastic floor and built myself a new one which included internal rebar type of structure.
I added some tiling and broke it up and added lots of damage.
With the floor in place:
I cut off a couple of pieces from the ruin which will get added to other rubble on the floor.
I think the plan will be to undercoat everything, paint underneath the floor then glue the floor in position and then carefully add the rubble on top of the floor and (again carefully) undercoat and paint the rest of it.
I need to attack the ruin yet with the dremel adding all the damage back in.
Quick shot with the Drone in place: