China paint on porcelain. Building up skin tone through multiple translucent layers of blushing. Three firings deep into the nine firings it took to complete.
I consider lashes and brows to be the hardest and least forgiving features to paint. They require the most technical skill, confidence, effort and nerves.
Before I begin, I spend a lot of time just looking at the face and visualizing where each lash will go, how thick and long it will be, in what direction it will extend and how tight it will curl.
Then I warm up my wrist and refresh my muscle memory by painting fast and free strokes for a few minutes, allowing myself the freedom to be imperfect, make many mistakes, be as expressive with the hairs as I want, wipe away and paint them over again, and again and again. I do it until my hand-to-eye coordination and my wrist calibrate to the pressure needed for the style of lashes or brows that I aim to paint. Practice really does make perfect; Quantity transforms into quality.
I usually take 2-3 firings to bring lashes and brows to fullness, so as not drive myself insane from having to start all over after every tiny hair mis-stroke.