First, wrap the wire between two dowels. Once you have enough lengths, slip one end off the dowel and place it into the chuck of a drill. Then gently spin the wire, remembering not to over twist as the wire will then split. You need only to have enough turns to make it manageable to use. Take the wire out of the drill and off the other end of the dowel.
Once you are happy with the way it looks then coat it in frame sealant mixed with a little bit of water to make a manageable paste. Please don't add too much as this will drag back down to the bottom. I normally do one layer then wait and repeat this until I am happy. Concentrate on building out the trunk.