Well, this certainly is open to some interpetation. But, as aircraft paint weighs about 4 - 5 lbs a gallon (depending on solids content and VOCs) and it takes about 10 gallons to paint a plane the size of a 109 (including primer) the answer is 40 to 50 pounds. Now, this is rough. It includes only one primer and finish coat. If the aircraft had extensive camoflauge in various colors it could end up weighing more. By the by, a flat finish cost about 5 mph on top speed and many pilots prefered to wax and polish their aircraft to gain back that performance.