I have on a smaller scale - I like your idea...
There is a company that makes an item called 'octa-hinges' and 'octa clips'.
I ordered sets from a math catalogue. The hinges clip to the cardboard
units, and fit together. You can construct walls with the clips, and doors
with the hinges. I can try to find the ordering information if anyone wants
it... We make small 'group' sculptures (everyone contributes a piece). The
little booklet shows kids making 'houses' and other structures... I like the
pizza cardboard idea. (I just gave my set to a primary teacher, they are
doing fairy tales and her kids are making a castle with them)