Thanks for the feedback.
This is the first time I try this technique, which is often seen on 1/35 kits, on a Braille kit.
It simply consists of very fine spots of oil paint (indeed) which you dapple on your kit. You then smear them down in a vertical motion with a slightly damp flat semi-stiff brush. You keep doing this until you can't really tell that the oil paint is there (cleaing the brush once in a while).
I hope this gives an idea. I am still practicing.