This idea stemmed from something I found in an industrial design catalog. It wasn't the furniture for sale that caught my eye, but rather the wall treatment in the background. They had used rough hewn lumber mounted over a concrete wall. Since I didn't want to redo the entire wall in my rental, I felt something more mobile would be appropriate.
Step 1: Lumber
For the trusty, reliable (and free) reclaimed lumber I nabbed a pallet headed for the garbage. Make sure to remove all the nails. I tend to get immersed in my work, so I forgot to take additional photos, but I used a table saw to cut pieces to a consistent size and a planar to smooth things out. For this particular project, an orbital sander should work fine.
Step 2: Steel Frame
Since I had scrap left over from a previous project, I used 3/4" cold rolled steel for a frame. This was roughly 20" x 50". When marking the hole to drill I took into account the width of the board as well as the gap between to make sure I had the center all down the length. MIG weld the corners and grind smooth so that everything lays flat (doesn't need to be pretty since it will be hidden). Proper work holding is important! Even with multiple precautions, the boards still started to drift towards the end and I needed to go back and touch up some.