This is what the back portion looks like that fits into the wall,.... never to be seen again!
These custom made grilles are made to order in just the size you need. The above is shown in the Como Block pattern. Constructed of Baltic Birch 1/4 inch hardwood ply, choose veneer of oak, cherry, maple, or paint grade wood. $1.75 per square inch of duct opening. Ships sanded, ready to paint or stain.