Alright, this is pretty sweet. Chicago kids designer/author Alyson Beaton is using Kickstarter to launch lille huset, a collection of flatpack, slot-together dollhouses made from paperboard and birch ply.
They're somewhere between permanent and recyclable, light and easy to manipulate, decorate, and modify, but sturdy enough to actually play with.
There are six different models, and two sizes, including a very little size that works for building cities and trainscapes. There's even a party pack, with little decorateable houses for invite/party favors.
It all looks very nice, if the selection is a little complicated. But they're also reasonably priced enough, especially during the Kickstarter phase, that you could consider buying a few, or a set.
Beaton's only $500 or so away from reaching her Kickstarter goal, so who knows, you could be the one who puts the project over.
Lille Huset slot-together dollhouses, starting from $10 [kickstarter.com via swiss-miss]