I'll be posting the moulding process next.
I wanted to show how I came up with the Big Tree sculpt from the very start...
I started with a preliminary sketch here: [link]
And then came up with a maquette concept here:[link]
The finished bronze can be found here: [link]
I wanted to post it so that if you are thinking of sculpting something large, maybe this will take away some of the intimidation factor.
The wire feed welder I used to put the armature together was really easy to learn how to use.
They can be purchased at any Home Depot or Lowes and usually cost from $400 - $600 depending on how good of one you want. Mine plugs right in to a regular wall socket.
The styrafoam can be purchased from the same place as well as the spray insulation foam.
Hope it makes sense and I hope you enjoy...