Polystyrene pellets are the origin of thousands of different plastic materials. These pellets are not unlike the ones found in many bean bags. An automatic system gathers the polystyrene pellets and sends them through a machine called an extruder, which melts them down so that they can be formed into whatever shape is desired.
The molds typically come in two halves. One half is curved upward, to form the fronts of the forks, while the other half is curved downward to shape the backs of the forks. The melted down polystyrene pellets are injected into the molds while the two halves come together, forming the forks. As the molds come apart, a cooling system solidifies the forks, and they drop onto a conveyor belt.
For fast food restaurants, hospitals, or anyone else who needs individually packaged forks, a number of the ones from the conveyor belt will be sent off to be heat-wrapped in polyethylene film by a machine that custom-cuts a layer of plastic for each fork.