I think a great addition to your mod would be either a single furnace that can be upgraded or an upgrade that can be applied to your current furnaces to add dye processing. This would add a second input slot for dye and a "tank" that when it consumes a single dye piece would fill that tank and then use it to dye the glass or terracotta coming out at a better rather than you could do by crafting it, this would also remove the need for hand crafting dyed glass and allow automated production of it. A super version of it would have a tank for each dye and you could select which to use at the moment. Possibly even turning each sand into "liquid glass" in an internal tank and then a selector to select output type, so regular or panes, glass bottles, etc, allowing other mods to add recipes as well like stairs, slabs and such, or their own secondary inputs to produce their modded glass in your furnace.