I know you asked about industrial oven, not household oven which obviously is often used, ...what have you come up with otherwise?
I know the PC I drop of larger parts has a furnace driven oven. I just made some parts for a friend making a cooker using the burners out of a furnace. I know my the PC's oven is large enough to drive a car in and he just has the outside lined with insulation. I would think yu could make something mid sized with bricks.