There are several types of forming methods for plastics: thermoforming, vacuum forming, and pressure forming. There are specifics to each type, but each one in some manner heats a sheet of plastic and drape it over a mold, using air pressure and male plugs to form the sheet into a shape. Virtually all thermoplastics can be found as a sheet and used in the forming process. However, forming is a single sided process which means that only one side of the plastic sheet can be controlled by the tool surface. The tooling cost for forming processes is generally cheaper than injection molding, especially for larger objects with lower complexity.