Our sofa isn't against the wall and there is a pretty good bit of space between the sofa and the wall so I decided I wanted to put a 6ft. long shelf back there under the mirror I have there currently. (Totally plan on replacing the mirror soon for something much larger.) I'd posted a pin to Pinterest a long time ago showing a shelf made out of pipe flanges and pipes with wood and finally decided to make one.
When I got home, I sanded the board and stained it with Minwax Dark Walnut stain. Robby installed the pipe flanges on the wall using sheetrock anchors and the shelf fit perfectly between the flange and the end cap. I used a sharpie to color in the head of the screws so it blended with the flanges better.
I'm only using it for decorative purposes so I wasn't really worried about it being knocked off the pipes. If this is a concern of yours, ask Mr. Google for solutions as there are plenty.
I like it and I'm going to make a wall of them soon, shorter ones though. Probably three of them about 3ft. each.