Airbrush, yes.
First base coat, in this case red and black on the legs. Once it has dried I painted the details with a small brush.
Now I am awful at painting details, so my trick is to paint the base colors and easy details, varnish everything with a gloss varnish, and then paint the difficult details on top of the gloss coat. That way when I fuck up I can clean it without fucking up the airbrushed paint and try again.

Also there are some details, like the light blue on the legs, that are surrounded by a small panel line, since I was applying a panel line wash afterwards it wasn't that much of a problem if the borders of the blue details were done perfectly, since the black line would cover it.

If you're using an airbrush and it's orange peeling like that, try using mr leveling thinner instead of just mr thinner. Assuming you're using lacquers like gunze. If you're using acrylics add some paint retarder.