The Cozy Mark IV is a 4-seat, single engine, homebuilt light aircraft designed by Nat Puffer, with parts and plans supplied by Aircraft Spruce & Specialty Co. The aircraft is built from plans using basic raw materials. It is not a kit aircraft, though many small parts are available prefabricated. The Cozy is similar in design and construction to the 2-seat Rutan Long-EZ, from which it is derived, with approval from Burt Rutan.

The Rutan Model 61 Long-EZ is a tandem 2-seater homebuilt aircraft designed by Burt Rutan's Rutan Aircraft Factory. The Long-EZ has a canard layout, a swept wing with wingtip rudders, and a pusher engine and propeller. The tricycle landing gear has fixed main wheels with streamlined spats and a retractable nosewheel. Its predecessor was the VariEze, plans for which were first available to homebuilders in 1976. The prototype Long-EZ, N79RA, first flew on June 12, 1979.