I do a whole lot of this metal surfacing work.... also have an entire foundry so when done it is by choice as it can do things that I can not get with conventional casting.
The bulk of the form above is very thin fiberglas for it's strength and lightness. The other forms weaving up off it are from other cast aluminum metal pieces.

The base for the piece is a head that is life sized and used as a stand. It matches my head size so I can work with it and see how the piece fits, feels and what any problems would be when wearing it.
A wind would be the worst handicap due to it's nature but there is also a psychological element to the wearer as the two horns on the headdress set directly in front of your eyes so vision naturally sees both with each eye and then a floating diamond vision that occurs from the two tips that seem to be there between them.

The head base was made before the entire piece. (I've done a number of headdresses... they all start this way depending on who will be wearing them.)
The main piece was done in wax and a plaster sand mold taken off only the face of it .
The horns and added sections were added to the wax and covered with suran wrap before the plaster was put on so they would lock into it on the back depths.
Then the wax removed via steam cleaning and the plaster dried.
Molten bronze was metalize sprayed into that one side making it about a 1/16 inch thick and then backed up with fiberglas.
That is a system where a metal wire feeds into the gun, is melted and sprayed out like paint at 2300 F.
The metal is backed up with fiberglas to make it strong but thin yet and the plaster mold removed entirely.
The rest of the piece was modeled in fiberglas and the square holes trimmed up.
Then the back side was cold cast metalized with powdered bronze with a polyester resin binder and finished off..
For that cold casting metalizing I used a clear and very thin and diluted (like almost water thin) coat of polyester resin.
You can also dye it with the metal powder or dye if desired but keep it's viscosity thin. Then as the surface sets keep dusting it with the metal powder to saturate it to the max. It may take an hour or more to keep track and keep dusting.
Once it is gelled the resin will set and start to lock the metal in. I use a super fine screen to sift the metal powder on.
I get about a 85 to 90 percent metal to resin surface that way and after about another day or two it is ready to hard buff and finish.
For that I do not use the standard wax based compounds as that will only wax fill it more. Instead do a hand held or power wheel brass wire brush scrub and burnish.
It has to be cured and your time may be more or less??? be patient. It is a key to success.

The final finish is a standard chemical patina and then a very dilute and thin lacquer (I use Incralac brand as it is made for copper based metals).
After another day or two do a fine thin clear wax coating if it is to be outside as that will help protect the lacquer as well.

I have covered a lot here.
Hope this gives a general concept as I'm leaving out a lot of more precise details.

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