Fabrication work requires component parts, but in addition to the essential electronic input, basic structural materials are also needed to create the physical environment. Many materials are utilised and these can be obtained in simple forms, ready to be cut, shaped and assembled as required. Various metals can be used, including steel, aluminium, copper and brass, and these are available in useful forms, such as tubes, rods, flat bars or sheets. Some angle and other profile sections can be obtained. There is a choice of finishes, such as polished, brushed, galvanised or anodised, and sheets may be perforated, expanded or even chequer-plate. Plastics of many types are also frequently used and are available in a range of different shapes and sizes, including sheets, tubes, angles and rods. There is a choice of many different kinds of plastics, such as PVC, acrylic glass, polyurethane, polyaryletherketone and polypropylene. Resin-bonded paper and cotton fabric boards are also available. Many other parts are likely to be needed, such as cabinet enclosures and circuit boards, along with many small structural and mechanical components.