Welcome to Oil Capitol Sheet Metal's Online Store for Rectangular and Round Ductwork.     ORDERING DUCTWORK JUST GOT A WHOLE LOT EASIER. Now, you can specify and purchase ALL your ductwork and accessories ONLINE, and have them delivered to your door.     OCSM is an expert in Ductwork Fabrication and Design. More than 250 years of combined experience in fitting design and manufacturing, give our personnel the ability to save you time and money.     Our CAD drafting department can generate AutoCAD shop drawings to make your installation easier and more efficient.     Experienced personnel, great service, and cutting edge technology combine to offer the best value in sheet metal products.