Take all your old frames and paint them the same color for a cohesive collection. We filled these with scrap booking paper. I got this idea from Nate Berkus.
Here is where I got the idea from. I used some old spray paint and paint samples to paint the frame and twigs which I screwed the smallest cup hooks I could find in to. If you find an old frame at a thrift store you could have a 100% recycled project.