So, i've taken a look at the files, and found no build bar .js or anything like the build.js for the live game. So, um. I don't know if this is a stupid thing to try and make, or ask about. But wanted to see if it was even possible. from what i have seen, just adding the csg to the images might do something, but i'm going to test that now. If someone could get back to be on this that would be great
My assumption is that file decides what brushes are in selectable in the editor. But that is just a guess.
heres a repo of a ui mod with a custom csg, https://github.com/dan-westall/com.pa.map.custom.csg.letters if you load this mod and go to planet editor your see it and be able to place it, i couldnt work out the texting in 3d max to finish it.