192 MECHAN ICAL SYSTEMS profile. The profile can then be cut to size, drilled, and tapped. Extruded alumi- num housings used to be very popular and were used mainly with moving mirror fixtures such as Cyberlights, Roboscans, Intellabeams, the Clay Paky scans, and more. The popularity of modern plastics has long since overtaken that of aluminum as far as fixture housings go, although aluminum extrusions and aluminum sheet metal are still used extensively in the underlying structure of moving head fixtures and for many of the parts such as color, gobo, and effects wheels. Die cast aluminum parts are less common for large parts such as housings, but they're becoming more common for small precision parts. Aluminum parts are die cast by injecting high-pressure molten aluminum into a steel mold (called a "tool"). It's then cooled, solidified, and extracted. Casting aluminum is cost- effective in high volumes and can achieve tight tolerances (high dimensional accuracy). Stainless Steel Stainless steel is an iron alloy with a minimum of 12% chromium, which helps prevent corrosion and oxidation. It's used primarily where high temperatures