I had planned on making my own rustic backboard but came across a pre-made one that was just the right size while browsing at Michaels. I found the "hello" at Hobby Lobby - it was already "finished" when I would have just preferred a plywood one but it was also the perfect size so... here they are.
I did a quick sand of the backing and then stained it two coats of Special Walnut followed by two coats of poly.
I debated on what color to paint the "hello" - bright yellow, white, or green. I decided on the same green that I had painted our front door - "Mountain Forest" by Behr. I was concerned that the darker green might not stand out against the walnut stain so I painted two coats of white on first so that I could distress the letters afterward to help define the edges. Three coats of green later and I started sanding down the edges. It turned out pretty well.
I attached the letters to the boards with liquid nails.
Now to attach the board to the house. I didn't want to permanently glue them to the vinyl in case the sign didn't weather well. I ended up using 3M Command Velcro Small Picture Hanging Strips. The wood letters were quite heavy so I over-compensated and used six. I attached them to the back of the board and pressed it against the house with maximum pressure for a minute. Then I closed my eyes and slowly let go... they held!!!