After my first real stunt ship - the inevitable NOBLER - my own-design list started in 1964 with the POLYGON. Span 124 cm, 6 to 6,5 ccm ( 35 to 40 ) engine; the original had a Fox 35, of course.  
In my eyes this kind of airplane is the absolute minimum for a capable aerobatic airplane. Rectangular wing, D-box construction, flaps, rectangular box fuselage, sheet tailplane and fin, upright engine. Fuselage mounted landing gear is still easier to build, but I wanted to learn how the gear legs are mounted in the wing. In my opinion such a design is a very practical entry into the world of precision aerobatics, and with the right numbers it can hold its own among more sophisticated airplanes.
Many years later I found out that the dimensions are very close to the “Oriental” design.