'Darkening' in the layers
I'm poor as dirt (the 3d stuff was almost cause for divorce!) but I'd offer a contribution of $200 if it could be added to Openbrush.
Image below, Primary Micropointillism (on three colors) Imagine that in 3D!
https://photos.google.com/share/AF1QipPF3Bmbfw3nENyU_5u0Yjzz5SQynnPZ-uUU0jlkMKx0VJfD2VjpOiqzsu9tJRX6dw/photo/AF1QipM0X4W3BSGi5JoAJ1vHDHLc4lOEsn2enrsZaXcB?key=bmp3cEZheHVuZ3YxcDFrN3YxcURkbjNOT3NsaDlR