Mix up a bucket of Plaster of Paris and place the bottom of the tree trunk into the
center of the bucket of Plaster of Paris (I used the plastic bucket the
Plaster of Paris came in). You could also use a small plastic pot.

I added a few rocks into the plaster to take up some space in the bucket, but this is unnecessary.

Place the bucket with the branch inside of your tall planter box.

Using frog tape, tape the branch to stand up straight and allow it to dry overnight.

Using packing paper, plastic bags, or paper shopping bags, pack around the
plastic pot with your branch inside. until the tree branch is stable and
won't move.

Using a drill, choose drill bits approximately the same size as your stems of the leaves and bare twig branches.

Next step, drill holes in the tree trunk (the top third of the large branch)
at an angle to look natural when you insert the branches. I made my holes 1/2"- 3/4"deep.
Drilling the holes on a downward angle also helps the branches to stay
in place.

Start by placing your bare branches on the trunk first, then add the stems with leaves.

Think about where you will place your tree, as this may alter the shape or
size of tree you want. My trees go up against my house on either
side of my front door, so I do not want a lot of foliage on the backside
of the tree.

Remember that the widest part of the tree should be at the bottom of your branches, and
there should be some height in the center of the tree.

Once you have placed most of your bare branches on the tree trunk, add your branches with leaves onto the tree trunk.

Be sure to step back and look at the tree as you are working. This way, you can see where you need to add more branches.