[barrrf]

I used to manage a fab facility that housed 6 manual welding bays, 4 robot welding bays, 1 Mazak lazer and 1 plas table - along with various saws, brakes, ect.

For the welding bays, during my tenure there, I calculated the approx. booth cu ft and purchased the appropriately sized air movers. We fabricated our own hoods. And we purchased new curtains not unlike the ones posted by Vince. The trick was keep the curtains just off the floor enough so the air movers would pull the air from the floor up through the over head hoods. That distance is also calculable.

Later on we added one more smaller manual welding booth which we build a down draft style table and portable filtration system kinda like what Greg posted. But we build the down draft system to cover the hole bottom of the table with the air inlet positioned above a trough so sparks, slag, ect wouldn't go through the filter system.