Sketch two half-circles and a rounded-off rectangle in the circle on the side of the car. Add rectangles for details on the tank's top and side. Draw two thin, vertical rectangles on both ends of the tank to make the supports. Finish them with an arched triangle. Draw a coupling form at each end of the car. These forms look like the end of a wrench. Add a turn wheel at the front of the car.
On the next page, we'll add some detail to the tank.