So I am making a mod, and I am wondering how you make a custom model and j beam? Yes, I know I am being ambitious
For making a model, you will need to learn Blender/3DS Max/Maya etc., but that will take months to become good at it. After that, you will also have to learn how to texture, which means you will need to learn how to use GIMP/Photoshop/Paint.net etc. As for jbeam, using the Notepad++ is a good start
basically it takes like a full year to learn everything. Don't make a mod now because its gonna be crap without learning the proper techniques.