Identify a key tool commonly used in surface preparation.

A sandblaster is a key tool commonly used in surface preparation because it effectively cleans, smooths, and prepares surfaces for subsequent treatments such as painting, coating, or sealing. The process involves propelling abrasive materials at high velocity against a surface, which removes contaminants like rust, old paint, and other debris. This method is essential in ensuring that the surface is properly prepped for adhesion of new materials, providing a clean and durable base for coatings.

The other tools listed have specific uses but do not serve the same purpose in surface preparation. A paint roller is primarily for applying paint rather than preparing surfaces, an airbrush is used for detailing and applying fine layers of paint, and a wrench is designed for tightening or loosening nuts and bolts, having no relevance to surface preparation. Thus, the sandblaster stands out as the most suitable choice in this context.