The Hopper Hideaway is a fun unique playhouse concept. The versatile design allows you to expand the Hideaway in any configuration you'd like. The starter set includes two cardboard houses joined by a tunnel in between. The houses have openings on all four sides in which additional tunnels (not included) can be inserted. The tunnels notch securely into the houses, and have a swinging door in the middle for more run-through fun!
Instructions can be found at http://www.catsandrabbitsandmore.com/hopper_hideaway1