Mottling on a bf109g10

You could try a small piece of spoinge and dabbing it on. Just make sure you don't have to much paint on it. Never tried it myself, but have seen it suggested a few times.

I'm with bish on this one. you can even try dabbling your spots while there wet with what ever thinner your paint needs to soften the mottling a bit. 

Here's my attempt. I imagined the guy with a large sea sponge and a bucket of paint. Scary, I had some time in this 262 and didn't want to mess it up. Practice, practice with a small coarse brush before trying it on the actual model. I finally got it down fairly well and got after it. On one hand it looks somewhat crude but on the other hand the overall appearance is somewhat striking when viewed overall. You asked, this is how I did it. One of my favorite models actually! There ya go.  

Max

that's a cool seem. I seen plenty of pics of Luftwaffe done by hand. 1 that comes to mind I believe was the battle of Britain was mottled with a sponge. both complete sides that guy had to have a sore arm after that.

I used a small piece of a make up sponge to do the camo on this Albatross. I tore off a piece and super glued it to a toothpick with the rough side as my painting surface. I dipped that in paint, dabbed most of it off until I got fainter blotches, then started my camo job. Repeat as needed...