Looks like the ash catcher is rounded so unless they are easily found used, I think it could be easily fabricated by someone with a planishing hammer and some basic sheet metal fabricating skills. In case anyone is interested in this technique, I included the video link to planishing below. Imagine recreating an entire missing part on an original 50s Weber with one of these! Anyway, my apologies to those who know all the vintage terminology and availability. Not my strong point yet. Enjoy the fix!