I have been doing it for 30+ years with no incident. The welding surface is 1/4" steel with bent up edges to keep sparks from hitting wood and there is a canvas apron covering the walls for the same purpose. Ventilation is provided by an overhead fan that draws air in thru a vent. Now I want to improve ventilation by reversing the fan, housing it in a wooden plenum chamber, attaching it to the vent and adding 3 flexible metal ducts that descend to the work surface. I want to make the chamber from wood because it easier to work than sheet metal and I have plenty of it. The chamber will be 5 feet above the work surface. Is it ill-advised to make this of wood? (I don't know why the pic is rotated - it is not on my computer.)