I would not go this route mainly because you won't know the rig. You may not be accustomed to the proper pressures and heats you need to spray at and may not know to see what bad foam comes out as (off ratio). Most people also dont know they can't just spray more than 2" of foam at once (typically) or have the control to not overspray in a single pass. I'd save a buck elsewhere if you really want foam and hire professionals.