It was made with a wood shingle. I made lots of them, but this is the only one I ever kept.
You can buy a package of wood shingles at any hardware store and they are quite inexpensive. After you pick out the shingle you want to use (in this case, I used one of the widest ones in the pack), start painting. Its really that simple.
Here's my finished design...
2 suggestions I would like to make (hindsight is always 20/20)
1) Paint your signs to hang vertically rather than horizontally. The shingles, are thicker on one end and thin on the other, so if you hang them horizontal (like this one), you'll have to bend your wire all kinds of wonky ways to get it to hang straight.
2) The thin end of the shingle (the right side of this example) is rather fragile and tends to break off a bit. I don't mind because I like the rustic look of it, but I would not recommend doing any real intricate detailing on that end if you will be mad when it breaks off :)