Cozy MK IV Experimental Airplane IMPROVED!

UPDATE 30 Jan 2026: It was pointed out that the left wing STEP file incorrectly had a flat on the winglet. 

The individual part files should already be oriented correctly for easy printing. You'll need generous use of supports for the Propeller. A brim on the nose, each wing, and body is highly recommend. I also recommend printing each wing as their own part, as the high aspect ratio make these parts prone to coming unstuck from the bed. If you'd prefer more aerodynamically accurate winglets I've also included a “NO FLATS” version of each wing.

The nose, main landing gear, and main gear fairing parts each get glued on with a drop of superglue. Don't forget to put the main gear wheels in first; if done right they should spin freely.

The nose gear gets pressed into the nose section. It's a tight fit.

CAD can be found here:
https://cad.onshape.com/documents/b61cd9a7ba1662c438ccd85b/w/84a2aa6c0fb095abbb6089cf/e/d9e4525c9ab2e2c13bcc6e6a

For few months, I fell off the deep end dreaming of getting back in the air in a budget friendly way by building a Cozy MK IV. Alas, once the build-fever wore off, I realized just how much work a plans-built moldless-composite plane would be, but out of that fever came this model that you too can stare at for hours.

For the uninitiated, “The Cozy Mark IV is a 4-seat, single engine, homebuilt light aircraft designed by Nat Puffer. … [It] is similar in design and construction to the 2-seat Rutan Long-EZ, from which it is derived with approval from Burt Rutan.”

Do not attempt to build or derive an actual aircraft based on these models. They are not based on officially licensed Cozy MK IV plans and no effort was made to ensure they are aerodynamically sound.