I have a darkroom book from the late 60's that talks about contour mapping with tissue over the negative stage to lighten areas.
Basic concept with contact printing frames for headshots before digital.
you could go to your local lab and make duratrans , dura clears, or inkjet masks as easy.
I like the idea of a colour material .. my thinking by making areas magenta or yelllow, or blue , green you could not only lighten darken but control contrast in areas.
Using the Lambda and making silver and colour prints via PS is where I am at these days.