hi.. i was wondering how do u guys get this kind of effect ?

http://www.track-link.net/gallery/1149

as most of the time mine will end up somehing like this, a flat little testure surface

http://www.track-link.net/gallery/1301

by the looks of it hes use a thging called preshading were hes covered either all the kit in a colour like black/dark grey or just sprayed over corners weld seams/raised detail then thinned his base colour paint right out and sprayed over it a few time but letting the darker colour show through giving it more depth you can also reapply the shading colour after the base coat has went on to bing it out a bit more, also think once you have sprayed your base coat on add some white or grey ect to the colour and spray the center of the panels/hull ect this will give a nice faded look to it

so can this be done only using a airbrush?

Pretty much, yeah...

I have decided to have a textured surface on a part of my tank, so I found myself gently putting my finger in the wet paint to displace it to make little humps and ridges. That is if you are wondering about the bumps..