If you need to use a paint that is not available in a spray but only a bottle you may have an option. You can get a self contained spray unit at Home Depot called Preval I think. It has a glass jar and a power head unit to do the spraying. They cost about 4 or 5 bucks. Now I am not saying they will do the job an airbrush will do I am only saying they are cheap and if you thin the paint it will work. I have used them to spray Duracoat on a couple of my guns and for that they worked very well. Never tried on a model but it would be better than using a brush. Brush painting something as large as a model car body is very difficult to do well. This is just my opinion and others may disagree. Good luck and let us know what you did and post up some photos.