I had to go searching for these, here's a Cardboard House I made for Cy probably 1 1/2 ago out of Refrigerator box:
Cut out doors, 2 windows, doggie door in the back. Siding was made out of strips of blue poster board, white poster board for the trim and windows. The window boxes are a shoebox split down the middle and we decorated with flowers and curtains. And of course a mailbox for his mail.