Check out this website in Mexico.
http://www.geocities.com/flyingconcrete/
Sprayed concrete (a little hand held 'tirolessa' sprayer from Mexico) over
1/4' galvanized mesh on a bent and MIG tacked 3/8" pencil steel armature.
I'm real impressed with the technique, but haven't had the opportunity to
use it yet. I'm thinking maybe some kiddies playgrounds or something? The
neat thing is the wilder the design, the stronger it gets. This is also how
Watts Towers in LA was constructed by a self taught artist.
Gary