Ofcourse the Box is paintable, I can add as many states as I want, I just try to keep the active/inactive states at a singular Byte, and I successfully did that with the Gearbox, with even one bit to spare (only 7 bits used for the whole active/clockwise/counterclockwise thing). Always just try to paint the thing, if it can have Covers it is very likely it can also be painted aswell, and if it has a Facing then it can DEFINITELY be painted. 
Also you can just put dye into a Bathing Pot and paint GT6 things that way, no need to Spray it on.
As for the Texture, you would be surprised how gear alike something can look by just alternating bright and dark pixels in a 4x4 shape with a static 2x2 center. I think the Player owned Safes have such a texture on them for the Number Wheel.
And yep, the whole thing improves the Steam Age massively. I still need to do a Rotation to Kinetic Push/Pull Piston too, unsure how I am gonna do that one later.