Creating a skin or livery for your truck in American Truck Simulator isn't as hard as it might seem. You'll first need two tools... An editing software like GetPaint or even Photoshop, as well as the ATS Mods Studio. Using ATS Mods Studio, you can download templates for the various trucks available in the game. These templates provide an outline of all the paint-able body panels which you can create a livery over. Once you have the templates, open this with GetPaint or Photoshop. From here, you can start getting more creative, by adding layers, fonts, decals, shapes, and so forth. Take some time, and after the livery's all complete, save it as a PDN and DDS file. You can then copy this file into the game's main installation folder to add the liveries into the game.