>>8743604Tamiya does transparent paint that apparently works pretty well if applied through an airbrush.
https://www.wonderlandmodels.com/model-paints/paints-glues/tamiya/acrylic/clear/However, i have no idea what would happen if you would apply them onto something that has a color already and is not just trans-clear.
I could imagine you can darken those blue windows down with a few layers.. ofc you need to seal it with varnish afterwards and i would only recommend it for display pieces, and not something you give your 8-year old to play with because that probably will rub off eventually.