Sheet metal processing is known as sheet metal fabrication. Specifically, it involves using sheets to create chimneys, iron drums, oil drums and jugs, ventilation pipes, elbows, flanges, and funnel shapes, among others. Key processes include cutting, bending, edge folding, bending into shape, welding, and riveting, which require a certain level of geometric knowledge. Sheet metal parts are thin metal hardware pieces that can be processed through methods such as stamping, bending, and stretching. A general definition is that the parts maintain a consistent thickness throughout the manufacturing process. The opposite of these are castings, forged pieces, and machined parts, among others.