The process of making the body for a NASCAR race car is incredibly labor-intensive. It takes the shop 10 working days to make and install the body for just one of these cars.
The shape of the car is mostly determined by NASCAR rules. These rules are encapsulated in a set of 30 templates, each shaped to fit a different contour of the car. For instance, the biggest template fits over the center of the car from front to back. When the template is laid on the car, the gap between the template and the car cannot exceed the specified tolerance. Each template is marked on its edge with a colored line. If the line is red, then the gap must be less than 0.07 inches (0.18 cm). If the line is blue, the gap must be less than 0.25 inches (0.64 cm). If the line is green, the gap must be less than 0.5 inches (1.27 cm).
The templates actually allow a little leeway in the design of the car. Because 30 templates are not enough to cover every inch of the body, some areas between template locations are not strictly controlled by NASCAR.
The construction of one of these cars has nothing in common with how a street car is made. With the exception of the roof, hood and deck lid (which are supplied by Dodge), all of the body panels are made by trimming and then hand-rolling flat sheet metal between the rollers of an English wheel, which slowly bends and curves the metal until the contour matches the templates and fits on the car.
After the pieces are shaped, they are welded to the car and to each other, using the templates to check their location. The seams between pieces are welded and then ground down so that when the car is finished, it is one smooth, seamless piece. The doors don't even open.
After the car body is installed and ground smooth, the car is primed and painted. All of the decals are installed, including headlight decals (NASCAR cars don't have headlights), which helps make the race car look more like a street car.
Not all of the cars are built to the same specifications. Some cars are dedicated short-track cars, and others are dedicated super-speedway cars. There are some major differences between the two types.