I've always wanted to be able to dye clay, mainly white for victorian houses, but also other colours to make walls look painted. This might be something to concider adding. Also, dyed bricks. Not vividly changed in colour, still natural looking, just slightly shaded.
When I thought about making stained glass I thought it'd be best if sand is mixed with dye before smelting to make the glass. Same would apply to bricks. Just my two cents.