Find an old toy truck with no value. Toy cars and trucks are mass-produced, and locating a scrap model is typically easy. Pull two wheels off of the truck to serve as the end points on the sprinkler system. Building wheels with glue and sticks or by shaping paper clips is also possible, but the abundance of existing wheels is a time-saver and the perfect shape creates a professional appearance.
The sprinkler line is the long tube that connects the two wheels. The pressurized tube funnels the water through spaced sprinkler heads. The irrigation model is not a functioning unit, and any round rod works well for the sprinkler line. Either use a small piece of scrap metal in a rod shape or paint plastic straws black and glue the ends together. Place each end of the rod into the wheel spokes to connect the sprinkler.
The sprinkler system requires a water source to pressurize and pump water through the line. Build a second line by painting plastic straws black. Put one end of the line into the outside spoke of one wheel. This line will run to a creek, pond or irrigation ditch. The line uses a gas-powered pump to push water through the system, but replicating the actual pump is not necessary. The line is partially hidden by the creek and foliage in the model.
Build a diorama to demonstrate the sprinkler system's functions. Place a shoebox on one side to create the background. Cover the walls with blue construction paper to represent the sky. Add mountains with brown paper, if desired. Cover the floor with glue and cover the glue with a thin layer of dirt and grass to represent the irrigated field. Glue a meandering steam or small pond on top of the field and place the sprinkler in the field with the line dropped on the water. The completed model demonstrates the process of irrigating a field with a portable sprinkler system.