This uses Space Age assets (the foundation graphics) without requiring the Space Age mod in any capacity, I'm fairly sure this is a licence violation

I used this texture as a placeholder. I'm currently looking for another texture to replace it with. If you know of a mod that has similar textures or how to license the use of an existing texture, please let me know. I just don't want to lock my mod down by requiring a DLC.

I don't actually think using the graphics of the DLC rises to the level of a license violation. It's not like this mod uses the assets to recreate them outside of the DLC, like if someone was trying to implement the elevated rails without requiring the DLC.

Probably still safer to move away from them as soon as possible, but I doubt the Wube team would crackdown on this mod for that.