I would think about using florist wire and florist tape that way you can bend the branches and make them as thick or thin as you need to make them.
Use a terra cotta pot and plaster of paris for the base.
As this is a centerpiece it will also make it more 3D.
HTH.
ETA - here is something similar in idea from Martha Stewart's show today
http://www.marthastewart.com/article...a-stewart-show - go down to where they describe how to make the branch.