upper level house with the top open. zip ties were used to hold the two sides of the top together and to hold the top to the sides of the house.

two level - 4x2 cage with middle plastic pipe support. built in 2007.

cubes were purchased at canadian tire.
coroplast, plastic pipe and wire shelves (for tops) were purchased at home depot.
home depot also sells the cubes.

plastic piping is actually for central vaccum systems. it's cheaper than pvc pipe and easier to cut.