This is a handmade model of a biplane. The spark plug has become the plane's fuselage, which has then been welded to bits of cut scrap metal to form the wings, propeller and undercarriage.
This is a particularly clean and well-presented example of spark plug art.
A biplane is a fixed-wing aircraft with two main wings stacked one above the other, giving strength but reducing speed. The majority of early aircraft designs were biplanes.
What condition is it in?
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