I got away from rattle cans when I was a teenager and painted my car with them. It didn't take long to recover the cost of paint, and that was when rattle cans were just over a dollar. Now they seem to be $7 thanks to the VOC rules. Now everything really needs to be a water base, which unfortunately is what methanol seems to be a solvent for. Even a small Harbor Freight compressor with a little tank and a touchup gun would be good enough for a plane for maybe $100. I got a 2 hp compressor, 35 years ago and never looked back. I oil spray three or 4 cars a year, paint cars, motorcycles, garden furniture, use the air hose to clean the shop, and planes. The air chisel gun is cheap, and cuts through sheet metal very fast with no chips and the scaler cleans rust from most structural steel quicker than anything else. Great investment over the years. Just oil spraying one car is $80 now, so the cost is really negligible over time. I find cleaning the guns easier than brushes as well, except for the Pasche airbrush with the extra needles. The automotive 2 part paints work well, but maybe are a bit pricey. Just a clear coat is good enough though for models.