Galvanized mild steel is the standard and most common material used in fabricating ductwork. This has been the industry standard for decades.
The ducts are often faced with insulating materials either inside or outside. They can also be double skinned with a layer of insulation in between the two metal surfaces.
Automated sheetmetal cutting is often performed with a CNC plasma cutter. The information is fed into a parametric program which outputs the components of the duct as individual parts. These parts are then nested
