I am currently fitting out my small shop. Its in 1\3 of a 24'x36' tin building with concrete floor. Other 2/3 is my wood shop.
I have hand built all I can and am now down to attaching a chimney to the hand built forge hood. It will vent straight up. I wanted to bend some 18g sheet in a hex column but its looking like I may be purchasing 10" duct. I'm thinking one section of "black" pipe then galvanized rest of the way up.