National Metal Moldings Corporation
Here are some postcards of National Metal Moldings Corp. advertising major buildings with their "Sherarduct" product.
The book "Vision & Enterprise: Exploring the History of Phelps Dodge Corporation" (By Carlos A. Schwantes) has a reference... apparently a copper consumer? In 1928, the company National Electric Products Corporation was formed, and it was ranked among the largest consumers of copper in the world. This company was created from three other companies that came under control because of their dependency on copper - These companies include William C. Robinson's National Metal Molding Company in Pittsburgh, the Habirshaw Cable and Wire Company in Yonkers, and the Inca Manufacturing Company in Fort Wayne.
( Google Link to this book : https://books.google.com/books?id=JDzY8-E4YMsC&pg=PA177&lpg=PA177&dq=national+electric+pittsburgh+national+metal+molding&source=bl&ots=Pu49iuUEoJ&sig=ACfU3U315qbI0vFuG9MKvBIxXkJt8XlY0w&hl=en&sa=X&ved=2ahUKEwiYppiAzZTgAhWyc98KHZGTCwYQ6AEwB3oECAIQAQ#v=onepage&q=national%20electric%20pittsburgh%20national%20metal%20molding&f=false )