Product configurators are a widely used tool to let customers specify an individual variant that best fits to their requirements. The basis for this is a productmodel that has well defined degrees of freedom and options and so describes the possible solution space. Related to this are design automation systems that aim atautomating the design process in order to mimic human designers and assist them in routine design activities. While a lot of configurators and design automationsystems is settled in the field of business to consumer applications, some implementations for complex goods like in plant engineering are reported. The present article reports about a design automation system for trash rack cleaners which are used in water management. The basis for the system is a knowledge-based engineering system which uses spreadsheet, constraint and macro technology to create a fully detailed CAD model of the trash rack cleaner.