Painting Hard-to-Reach Areas with Spray Can?

Different nozzle styles can give different paint spray patterns from rattle cans of spray paint. Try version types, e.g., thin tubes.

You can use a piece of cardboard held above an area you wish to protect as a "soft mask" to prevent excess paint getting to areas where you don't want it to go.

You can extend this technique to cutting an appropriately shaped/sized  hole in a piece of cardboard and holding it over the area you want to paint.

Using thin tubes is a great idea!

i tend to brush paint those areas first, for example under body and axels of most warwheels. that way when i spray i don't have to worry about everybit of surface and the possibility of too much paint and runs..