Guys!
These nylon horns are horrible--heavy (several grams with the screws) and butt ugly!
I'm cuting my horns (better to say, my plane's horns) from old computer boards (where else can one get thin fiberglass?) and glue them to the structure. Yes, it takes time to dremel them out and to drill the holes, but the result is worth the efforts.
Just my .02 worth,
Boris