Wow! Your side air brush work looks like it was air brushed on.
Thanks. The camouflage mottling is the most difficult and time consuming part of doing Luftwaffe skins.
I use a Wacom brand pen and tablet for free hand work. It's so much better than a mouse.

In Gimp, I select the airbrush tool and set the brush size and opacity for the desired level of overspray. On the 110 it's a 15 pixel fuzzy circle set to 30% opacity. For the RLM 70, I set the opacity higher and used a smaller circle.
With these type of schemes the mottling can take upwards of an hour per color, per side, to get right. The 110 is particularly challenging since there is a seam in the bitmap that runs from the prop spinners to the gauge cluster on the nacelle sides. This make blending these mottle shapes incredibly difficult. I figure the total time making the mottling on this scheme is about 10 hours.