I saw bulletin boards similar to this in an online catalog for something like £70. I decided I wanted three.
Mine are about 18" across and are made from scrap foam-core (work), an irregular chunk of quilting cotton(stash), a printed cotton napkin/handkerchief (stash -- why do I have a stack of these?) and yards and yards of 1/4" elastic, most of which I already had. I confess, I did have to buy some additional black once I realized how much I was using. I also bought an electric staple gun. Maybe I was going to get one anyway, or maybe this was my excuse... Either way, how cool are electric staple guns?
Rather than cutting strips of elastic to length, I wrapped them through the center, all the way around. Used more elastic, obviously, but saved time, effort and staples. And since the staple gun was my BFF that weekend, it was my priority.
They are mounted via ribbons stapled (shocker!) to the backs and the hung on picture hangers.