We made eight baby bunnies, so we designed the house with eight rooms, one for each bunny.
And we opted for an open concept, i.e. without exterior walls, for easier play. We also made the roof removable, in case the girls decided they might want to wallpaper the interior walls later. Or paint them.
The house was constructed from flat cardboard sheets, rather than from a box.
We made 4 slotted two-storey walls, one slotted middle floor, one ground floor (same size as the middle floor, but without slots), and a roof.
Then we assembled it by slotting, and then gluing in place.
I used single-wall corrugated cardboard, because that's what I had large flat sheets of. Which needed support. So I added these props.
We wanted ceiling lights in the upper floor, so we poked holes and taped a string of IKEA's Strala lights into them.
Then the slanty sides of the roof were glued on, and the entire roof balanced on the top of the four walls.
Later, the girls decorated some tea lights with fancy paper, and glue-dotted them to the walls of the lower storey, for light sconces. Those little square holes in the walls were to allow us to switch the tea lights on and off from behind each wall.
Since then, the girls have made some cardboard furniture, but otherwise, the bunnies just snuggle in cloth napkins and washcloths on the floor.