I made a post of this bevore but I will try to be more clear now.
So you can make these mods / texure packs but there ia no easy way to do it as far as I know.
So will it be posible to make a app or function so it will be easier to make them
I will make it very clear. I have no idea if this is a thing alread. If yes pleas let me know
Use Inkscape. It's a free svg editor, and there's lots of resources (build tiles, etc) on these forums to use with Inkscape