Hey Uwe, for some reason, FB links don't work really well. If you have more pictures, maybe edit this post to remove the FB links and replace with the pix!
I've been thinking about a working miniature paint stencil. A 3D printer is the key to this. However, it needs to be printed very thinly, about 0.2mm. I then applied a spray adhesive to the back so that the paint doesn't bleed through it later.