I am just starting an "epiphyte tree" for out on the deck (Lord knows what I'll do over the winter).
The glazed terra cotta planter has four drainage holes, so I covered them with masking tape and stuck pieces of 1/4" polyethylene tubing through them.
I drilled two holes horizontally through the base of the driftwood and inserted two very long lag bolts to provide some lateral stability, then after positioning it in the planter, I filled it with quick-set concrete, the kind you pour in dry, then cover with water to seep in and cause it to set. The damned thing weighs about 25-30# now.
Once the concrete had set (30-45 minutes), I extracted the PE tubing, so now it has drainage paths through the concrete.
I'm going to start with some tolumnias as well as tillandsias and branching neoregelias on the branches, and may plant something in the moss I'll place in the pot on top of the concrete.