Look what I found... on the internet!
They call it the "Spielkissenhaus" from Nestrocker - a house made up of five modular square mattresses and one door-element. Through Velcro connections, you can build your hide-away or dream house as you wish.
The Spielkissenhaus comes in three color combinations, but honestly is bit pricey. Nevertheless, i like the concept a lot. Build a castle or lay the mattresses flat on the floor for gymnastics or sleep-overs - a truly multipurpose MINIHOUSE!
(Please note that I am not sponsored in any way, I just like to share what intrigues me as architect, designer and mother.)