Like this cool banner from Design*Sponge.
We decided that we would build a frame with some wire that we could use a clothespin to hold them on. We built the frame using 2x2 boards.
She had a couple requests, one that it needed to hold about 30 postcards and she wanted it painted a burnt orange. I already owned a orange color paint at home from when we painted our laundry room. It isn't burnt orange but at least it is in the orange family.
Then we used eye hooks at the end where we tied the wire into the frame. You have to pull the wire super hard to get it straight. Of course once it's get bent, it is never going straight again.
We used the clothespin's to hold the postcard in place.
So.... here is the final project.
I think it turned out pretty well. It also is located in a good area where her postcards can be a conversation piece.