I spent a fair amount of time patching holes in walls and removing blue tack stains. To avoid this I was looking for a quick solution to hang pictures that would make my life easier when it would be time to repaint my daughters rooms.
I picked some poplar boards (2″ by 3/4″, really 1 1/2″ by 1/2″) and cut them in 2′ sections. I used a table saw to cut a groove in the shelves to hold the pictures in place.
The frame is holding with wood glue and finish nails (I used a nailer to go faster). To hang the frame, I screwed a couple hooks on both sides and attached a metal wire between them. I added two small felt pads on the back bottom corners to prevent scratches on the walls.
I built two, one for each kid. It didn’t take much time to get them filled with pictures, I might have to build a few more.