Cardboard, gesso, paint, glitter and loofah, mostly. http://www.papatedsplace.com has examples. Mine were originally my grandmother's purchased mostly just after the War.
The windows and doors mostly need replacing - they've baked dry over the years, and eventually just crumbled.

They fascinated me as a child, and still do. They're part of my primary process material, the little houses glowing from inside, and the smell of baked cardboard and the C6 lights that looked like glowing candy, but were too dangerous to touch. They've got nice ceramic ones at the store, but I like my cardboard houses :)