Is it possible to create a shadowvolume from a duplicated mesh? I believe you have to remove the textures from the model but I don't know how to do that in Mod Tool.
The shadow model needs to be renamed to sv_ and may have any name. Like if it calls Tank, then sv_Tank will be the shadow.
I got that bit, but I'm not sure if it's 'okay' to have it with a texture: As I already merged my models together, I just created a duplicate and polygon-reduced it but the shadowvolumes I have seen have no materials assigned to them. I want to remove all materials from the shadowvolume mesh.
I guess it's ok, but textured meshes makes the models more bigger in kb, and probably takes more unneccesary game memory. To easy remove textures, just copy the model, translate it in any direction, and merge it with original without merging textures. Then delete unnided "duppleganger" polygons.