I'm about to start down the path of designing and constructing a custom dollhouse for my daughters. It will be a 1:12 model of our current home - a traditional colonial style 2-story home.

I have not yet answered for myself how I will design access -- the standard open back won't suffice given that there are rooms in the front that would otherwise be accessible only through doorways. I may make it a traditional open back, but then also have the front walls on hinges to open up access to the front. Has anyone done this before?

Before getting to that point though - a question more pertinent to this early design stage: what wood is best for the floors and exterior walls? I don't want this thing to be too ridiculously heavy, but at the same time, I want it to stand up to the use of a 4- and 6-year old and stand the test of time. I'm leaning toward 1/2" baltic ply for the primary structure (floor and exterior walls) rather than some form of MDF or other products that could swell substantially/permanently if they get a few drops of water on them. I like the stability of MDF against warping (versus plywood), but I don't care for the weight and the susceptibility to moisture...