The shelf is 12" deep and spans the inside of the frame. I used scrap wood that had been cut down for side supports and under the shelf. The shelf itself is 1/2" ply and the back and sides are 1/4" luann ply.
Here's the back. It makes the duct look better by hiding it.
Here it is back in it's home, and the paint in place. I may add some boxes to hold the paint for ease of removing them. You could also brace the sides and make drawers and use drawer slides from Home Depot as well.
