** Install a 4" ventilation duct and fan in the clean CNC room to be used by the laser. The roof perforation will be done by a professional roofer. Interior ducting can be done by volunteers. Makeup air? Materials: ducting, elbows, hangers. $300 | ** Install a 4" ventilation duct and fan in the clean CNC room to be used by the laser. The roof perforation will be done by a professional roofer. Interior ducting can be done by volunteers. Makeup air? Materials: ducting, elbows, hangers. $300 |