I used 4 branches of manzanita from here. I bought the ones that were painted silver but this will work with the natural ones too. I arranged the branches and then used wire to fix them together. I stuffed paper into the urn to hold the arrangement in place and then I poured plaster of paris in to set it.
While I wait for my shipment of shiny crystals to arrive, I'm working on tags that guests will fill out and put on the tree. The tags say "Chloe and Sebastiaan are..." and the instructions will say to fill in the cards using 5 words or less.
As you can see, I have a lot more to go.