Some ideas regarding paint:
- Ability to mix paint similiar to hair dye
- White paint
- Ability to paint background only or block only (Paintbrush for blocks, a new item for wallpapers? Perhaps combine them like Diamond Horns and Will of the Wild? Two separate items would work fine too, but this would be sligthly more convinient.)
- Transparent paint (Paint diluter; would make placed paints have a weaker effect, not for making blocks transparent. That's not how paint works.)
- An item that functions like an infinite supply of paint: you could choose from all existing paints (and combinations) and paint indefinitely with it. This however would have to be quite expensive, I would say in the range of 10-20 dls as less than that would be kind of op and more simply wouldn't be affordable for most builders.

might update this later, share your feedback