well, first you are going to need a Scripts/Ships .py file that will point to the Model, Hardpoint and other stuff for the ship, you can make that by looking at the other scripts in said file then once that's done (assuming you've already got weapons files and an AI) is to use BCSMC to make a .py for the Scripts/Custom/Ships folder which tells the game where to find your new ship, and where to put it in the menu