Ok, so to make our own "material" I just add it in the Materials.ini in Base.rte right? And from there I can just define all the variables for the material?

And whatever material I want to use for my mod, has to be in materials.ini?

Just asking for clarification.

You don't have to alter Materials.ini in Base.rte. You can put it in a seperate .rte.

What he said, but make sure it has an Index that doesn't conflict with the base materials (they can't have the same Index number)

Unless you're making a scene or bunkermodule, it's not necessary to actually define a new material. Just use a CopyOf and modify the specific attributes you need. That means no hassling with Indexes.