I think the real trick would be finding some of the stuff on the site Gary linked to that is aluminum and not plastic. That vent in the front is just made to kick when you walk into the coach and I have no doubt it will fail again. A metal one would be much more robust but slightly more difficult to make.
I re-glued the one I got from Marathon last night with some super magic glue stuff I bought at Oshkosh. I'm glad I had the parts alligned because it instantly stuck (I had sprayed the big plastic piece with some kind of glue primer) and it was unmovable.
I saved the big plastic pieces off of the old part so I can make a suitable replacement when we get the new stuff. Maybe I can make it till OKC without breaking this one.
