At about 24 square feet, the Gypsy Junker, made primarily out of shipping pallets, castoff storm windows and a neighbor’s discarded kitchen cabinets, is the largest of Mr. Diedricksen’s backyard structures. The Hickshaw, a sleeper built on a rolling cedar lounge chair (or as Mr. Diedricksen calls it, “a rickshaw for hicks”), is considerably smaller, at 2 1/2 feet wide by 6 1/2 feet deep. The Boxy Lady, two cubes on a long pallet, is the smallest: 4 feet tall at its highest point.