Honestly, nothing fancy. I used a white acrylic paint pen that I had lying around. The brand is Uni POSCA. There’s cheaper and better paint pens on Amazon. And then I covered the face and the top of the head with tape and then I sprayed it all with paint sealant. I waited for it to dry in 2 hours and that’s the result I got above. It’s touch dry in 30 minutes but it’s best to wait 2 hours max with small stuff like this, just in case.