Personally I use a combination lens holder / air assist I got from lightobject and use an airbrush compressor for air delivery. It works well enough to keep the bottom of the lens clean and to keep flame ups down.
But, like I was saying, it’s not really efficient for the purposes for getting air down into the cut line. You really would near something like this thing from thingiverse. https://www.thingiverse.com/thing:869652
That uses some 3d printed parts, but you get the idea. You would just have to come up with away to attach the tubing to the head. That part used 1/4 inch copper tubing and it’s got a added printed nozzle. I would think 1/8 tubing would work as is, which is why I was saying brass tubing like you can get from a craft store. You can also get a small tubing bender fairly cheap from harbour freight. I’m sure somebody has done something like this before (pretty sure I’ve seen it somewhere) so you may have to search around.
Air supply comes down to an air compressor, airbrush pump or a large aquarium/pond air pump.
might want to start a seperate post if you want more ideas for this type of air assist.