Hiring a fabricator gives you access to Carbon's new Autosculpt feature, a comprehensive tool allowing you to shape many physical aspects of your vehicles. It's quite similar to Oblivion's slider-based character customization tool. A huge number of body attributes including rims, tires, hood, side panels, intakes, spoilers, grills, and many others, can be tweaked by way of realtime slider controls. Spoilers can be enlarged, intakes can be widened, wheels can be deepened, the front grill can be shrunk down a bit; there are a huge amount of changes that can be made to each vehicle. However, the changes are purely cosmetic and do not affect gameplay in any way.