I started with a cheap mirror base that I picked up at a discount store. Popped out the mirror. Next have a good stash of driftwood. I love medium size sticks, from straight to curvy. I left the mirror base black, but you could paint it white. Next I used small nails with heads. The job would be easier if you had a nail gun.... next time.
Then just start nailing them to the mirror base. You may need to use a few nails in each piece.
First round of driftwood. Then go back and find the perfect pieces to do another layer, just to cover the black background.
All done! Put the mirror back in and since it already had a picture hanger it went straight on the wall. Another fun idea, would be to spray paint the wood all one color, striking white or bold pink.
I love the little piece of driftwood on the left that has a bit of green and white paint.