how can i do panel lines on a plane etc without an airbrush?

Oil paint, pigments, pastels.

i dont have any of those , i was wondering if any ones ever tried acrylic or enamel paints with a brush before they paint the whole model.

well you could do it with a brush, you could go with black paint over all panels using a very fine brush. The problem is the coat of paint you put over it. When you use an AB the coat is thin enough for the black to shine through. When you hand paint this coat is usually to thick. The effect of the black would be invisible. I would rather just paint the whole plane in the colour of your choise, and then use a lighther version of this colour in the middle of the panels. Make sure you feather it out and use multiple thin layers. I would enamels for this. If you see brush streaks afterwards you can sand them off with a very very fine wet sandpaper. That's an old trick.

Matthijs

You can use this method:

https://armorama.kitmaker.net/forums/205496&ord=&page=3

The wash was applied, and then removed afterward, leaving the color only in the recesses. I've seen it used on aircraft as well, and it makes for very pretty, but IMHO very unrealistic finishes on aircraft. The panel lines are so subtle on aircraft you they rarely show up when you view them from 32 or 48 feet away.