Its a big beast

Are you going to hook the future builds to this one? If so, it might be good to just paint the MDF to keep dust down and then decide on finishing the outside when you do the other rooms.

No This will be self contained and will support 2 existing builds not future ones.

Faux doors, windows and exterior could be a possibility, like with Eric Lansdown houses. I absolutely love what you have done so far, this is going to be wonderful!

That's a good idea Debora, I never thought of that.

wow Jo, it is such an interesting project.

I agree with debora for the outside, a second choice is to paint MDF with a plain colour

Thanks Sergio. I could paint it or maybe decoupage the outside or just paper it with something pretty and wipeable. I've seen faux door and window prints that would be a possibility too.

Actually an old fashioned Boston night time scene papered on the outside would be wonderful, heavily varnished to protect it - hmmm - cogs are whirring.