Custom-designed powder coating systems include the pretreatment washer, dry-off and cure ovens, and material handling system typically installed in an environmental room to ensure trouble-free powder application and dirt-free parts. These rooms are equipped with automatic climate-control systems designed to maintain an environment at optimal coating conditions. Ambient air in the room is maintained at uniform temperature and humidity throughout the day and all areas of the room to provide ideal powder paint or enamel application conditions. It is constructed from modular insulated panels, with all internal surfaces reasonably smooth for easy cleaning.