Does anybody have any any information on the construction techniques that RCA and Frazier used on their threater horns (e.g. RCA Ubangi)?

I've seen a pict (http://home.att.net/~lkalin/photogallery.html) (Michael Christ) where it looks like he's reproducing the rigcage curve of some alien cow-being: elegant but not commercially viable. They must have had a relatively quick-and-dirty technique to build a commercial product.

Any info deeply appreciated.